TBH I mostly like older bikes for their looks, simplicity and lack of doo-dads.

Anyway...two unrelated questions.

1. Do you think the 2011 Allez work-out as a stand-in for a "classic frame" for my Dura-Ace 7401/2/3? I'd strip and replace the parts obviously. Throw my 7400 I've been coveting on it and it's pass muster, hm? My major concern? 1 in. threadless headset, WTH!?

2. Was the Cannondale R500 the higher-end of the series when it was new?

R500 was mid range, but the only place most Cannondales varied in a given year were components.

There was a thread discussing the new steel Allez (I assume you're referring to this one?). The consensus was a TIGed release was a poor reissue of their classic and not worth the asking price.

I have not read the thread; a link would be great.

Anyway, it's an R300, and when you put it next to my friends R500, frames are the same exact thing (mine is smaller).

Any difference in how they were made/materials?

No, frames are likely identical. Components were the only thing that differentiated models (within categories that is..R400 vs T400 would be different frames) for C'dales of that era.