Is the "inter partes review" of the AIA constitutional?

In a post titled A Constitutional Challenge to Inter Partes Review   , PatentlyO
talks about a brief by Ned Heller asking the CAFC to find the inter partes review component of the AIA unconstitutional for violation of the Seventh Amendment right to a jury trial.  IPBiz recalls the constitutional challenge to the copyright law mounted in Eldred v. Ashcroft.  CJ Rehnquist noted the grant to Congress was general and Congress was "free to run with it in many respects." 

If one looks on the internet for a discussion of 7th Amendment rights, one may find something like

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Application of the 7th Amendment

When does the 7th amendment apply? There are four criteria for you to be able to have a trial heard by a jury under the 7th amendment.

1. First, your claim must be a civil claim as opposed to a criminal claim. This essentially means you are seeking money to compensate your loss from the person you are suing.
2. Second, the claim must be based on federal law and be in a federal court. The 7th amendment, believe it or not, does not apply in state courts. Some states, however, have adopted the right to a jury in civil cases.
3. Third, the lawsuit must be more than $20. Interestingly, $20 was a decent amount of money when the Framers wrote the Constitution. Nonetheless, despite the depreciated value of $20, it is still the threshold used to decide if a trial by jury is allowed.
4. Finally, the lawsuit has to be a claim for which the English common law of 1791 would have allowed a jury trial. If the English common law of 1791 would not let your claim go to trial, then it cannot go to trial by jury under the Constitution.

--link:  http://education-portal.com/academy/lesson/the-7th-amendment-definition-summary-court-cases.html

From the Markman case, we know that the 7th Amendment applies to patent infringement case; from Wikipedia:  The 7th Amendment guarantees the right to a jury trial in patent infringement cases. The 7th Amendment preserves the right to jury trial as it existed in 1791. There is no dispute that infringement cases today must be tried by a jury as their predecessors were in 1791.

But, is there an English common law counterpart to "inter partes review" which existed in 1791 and which allowed trial by jury?  

Judge Pauline Newman wrote in Patlex v. Mossinghoff, 758 F.2d 594 (Fed. Cir. 1985):

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In contrast with the private rights at issue in Northern Pipeline, the grant of a valid patent is primarily a public concern. Validity often is brought into question in disputes between private parties, but the threshold question usually is whether the PTO, under the authority assigned to it by Congress, properly granted the patent. At issue is a right that can only be conferred by the government. See Crowell v. Benson, 285 U.S. at 50, 52 S.Ct. at 292. Thus we find no constitutional infirmity, under the analysis suggested by Northern Pipeline, in patent reexamination by the PTO. 

The holding of McCormick Harvesting may also be distinguished, in view of Congressional intent to provide a separate procedure for reexamination while preserving the reissue practice. The purpose of reissuance of patents is to enable correction of errors made by the inventor, at the initiative of the inventor. The reexamination statute's purpose is to correct errors made by the government, to remedy defective governmental (not private) action, and if need be to remove patents that should never have been granted. We do not read McCormick Harvesting as forbidding Congress to authorize reexamination to correct governmental mistakes, even against the will of the patent owner. A defectively examined and therefore erroneously granted patent must yield to the reasonable Congressional purpose of facilitating the correction of governmental mistakes. This Congressional purpose is presumptively correct, and we find that it carries no insult to the Seventh Amendment and Article III.

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Within Crowell, one finds the text:

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As the claims which are subject to the provisions of the Act are governed by the maritime law as established by the Congress and are within the admiralty jurisdiction, the objection raised by the respondent's pleading as to the right to a trial by jury under the Seventh Amendment is unavailing ( Waring v. Clarke, 5 How. 441, 459, 460 (1847))
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As a footnote, Mr. Reverdy Johnson represented the appellants (Waring et al.) in Waring v. Clarke.  [Johnson defended Sandford of the Dred Scott case; as a US Senator, he was a pall bearer for Abraham Lincoln.]

From the earlier post on IPBiz Bilski: which elements from Eldred will return?
  
:
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Further to the IPBiz post titled
On horse-training methods and Bilski oral argument , one recalls the exchange between Chief Justice Rehnquist and Professor Lessig in Eldred v. Ashcroft:

MR. LESSIG: Well, if it flies in the face of what the Framers had in mind, then the question is, is there a way of interpreting their words that gives effect to what they had in mind, and the answer is yes.

CHIEF JUSTICE REHNQUIST: Well, you know, certainly what is happening in the country today in the way of congressional -- under the Commerce Clause is totally different than what the Framers had in mind, but we've never felt that that was the criterion. What the Framers thought of, there weren't steamboats, there weren't railroads.

MR. LESSIG: That's right.

CHIEF JUSTICE REHNQUIST: We've said there was a general grant, and that Congress was free to run with it in many respects.

Another interesting exchange:

MR. LESSIG: That's right. That's the important hurdle, and we'd like to jump that first, but the other ones, Justice, you're right, in 1831 and in 1909 Congress extended terms in a way that is inconsistent with the strongest form of the test that we have advanced. Those extensions, however, were never challenged in any court and certainly not considered by this Court.

CHIEF JUSTICE REHNQUIST: Well, doesn't that itself mean something, Mr. Lessig? The fact that they were never challenged, perhaps most people, and perhaps everybody felt there was no basis for challenging them.

MR. LESSIG: Well, Mr. Chief Justice, it's absolutely true that this case is here because of a fundamentally important changed circumstance that makes the Framers' limitations on the Copyright Clause much more significant. This is the first time I can remember where this Court has been pointed to changed circumstances as a reason to reaffirm the Framers' values, because for most of this period, Mr. Chief Justice, the only people who were regulated by copyright law under the Copyright Act would have been [*4] commercial publishers, primarily, and now for the first time the scope of this exclusive right has expanded because of the changed technology of the Internet to reach an extraordinarily broad range of creativity that never would have been imagined before.

Now, it's not the case that the earlier extensions were not questioned on constitutional grounds. In fact, Melville Nimmer, in the consideration of the 1976 act, suggested they were plainly under --

CHIEF JUSTICE REHNQUIST: Well, I'm talking about court challenges, not academic challenges.

IPBiz notes the existence of Lawrence Lessig's article, "How I Lost the Big One," [ Legal Aff., Mar./Apr. 2004] concerning the outcome of Eldred v. Ashcroft, which includes the text:

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