Hey y'all, I posted this in the Bonjour from Babolat thread, but figured it would be appropriate here as well.
Based on feedback, I went ahead and grabbed a 4 3/8 APD 2013 from stock and a 4 3/8 Pure Aero Tour. I measured both, with the replacement grips on and off, and here are my results:
APD 2013 (4 3/8)
Grip on
-Middle of handle: 4 3/8"
-Bottom of handle/near butt: 4 3/8"
Grip off (bare handle)
-4" along entire length
Pure Aero Tour (4 3/8)
Grip on
-Middle of handle: 4 3/8"
-Bottom of handle/near butt: 4 1/2"
Grip off (bare handle)
-4" along entire length
In other words, the measurements of the two were identical, with the exception of near the butt of the handle.
Thus, it seems like the grip was wrapped with a bit more overlap on these Pure Aero Tours, and folks are finding it to feel bigger, especially if they hold their rackets near the bottom of the handle. Plus, like you said, these grips compress down, so people who are used to a compressed grip are using a new, noncompressed grip, which makes the grip size feel even bigger. I would say that it's probably a combination of these two factors.
I tend to hold near the bottom of the handle, slightly hanging off the buttcap. What I did with mine was rewrap the base grip with less overlap so it felt less bulky. I ended up cutting off the excess, and it feels much better. But, I still prefer the 4 1/4 grip these days.
Hope that helps!