Good points, Jonah. I don’t think that it should be a deal-breaker for anyone in 2012 that Gingrich called Reagan’s foreign policy a pathetic failure while the latter was president. But it does add to the pattern of grandly asserted bad judgments by the candidate.
It also raises the issue of Gingrich’s grandiosity in another way. Gingrich was in general an ally of Reagan and did a lot in the 1990s to extend Reagan’s good work — and Romney can say neither of those things. But Gingrich cannot leave it at that: He has to, as you put it, present himself as a “junior partner” to Reagan in the ’80s. (And often the “junior” goes unsaid.) This tendency of Gingrich — an exaggerated form of a tendency common to politicians — does him no favors, and won’t do any of the rest of us any favors if he’s the nominee.