So after much complaining on my part, I thought maybe I should get some wookies together and take a pic, to see if indeed there is much of a size discrepancy with the new figures? Well, the photo below (I'm working on getting better, but seem to be getting worse) shows what's up:

From left to right are:
Chewbacca Mechanic POTJ
Chewbacca VOTC
Chewbacca Mynock Hunt
Chewbacca POTF2 - freeze frame
Chewbacca ROTS
Wookie Warrior - ROTS preview
Chewbacca - vintage (yeah, I need a new one for sure)
Yarua - post-OTC
So originally it looks like Hasbro had Chewie pretty much in line with the vintage, in terms of size. That's a bit ironic anyway, given the early POTF2 stuff was huge. I haven't actually opened my original orange carded Chewie, so couldn't do that comparison, but I'd bet he was bigger than the POTF2-FF version.
Mechanic Chewie, Mynock Chewie and VOTC Chewie are pretty consistent, both in terms of height and bulk. The ROTS figure isn't
that much taller than its recent predecessors but it is considerably more bulky, IMO. Basically it's like he put on about 25% more body weight in the evolution process, or perhaps he goes on a major diet post-prequel.
Yarua is just plain huge, a complete monster and the Warrior is that much bigger again

In general then my initial feeling upon opening these is that Hasbro did indeed throw the scale out the window in an attempt to make these things bigger. Big boo on that one then, it is really disappointing to me. I suppose it remains to be seen what the scale is in the movie, but I was more concerned with the scale from a figure standpoint

I was surprised to see the highlights to Chewie's fur started in the VOTC version and to me aren't that different in the ROTS version. Definitely lighter, but they were largely present in a previous version. The other Chewies are pretty consistently dark, so another lack of attention to detail knock I suppose. I imagine the brain trust thinks they're getting more accurate, but that's a wee bit open to discussion.
BTW, not sure if this belongs here or not.