In my opinion the only difference between the Schott 141 and 641 (or 641hh) and is that 641 fits one size smaller. As I understand size 44 in 141 has the same measurements as side 46 in 641. That's not in fact slimmer fit if but it is the same jacket size smaller. Schott could label their jackets in correct size. Same thing with 626vn. Why put a size label before factory vintaging process if the jacket shrinks one size smaller as is stated?
The thing I don't like in my 641hh, is the huge gussets in bi-swing back. Those batwings look like from Thriller video. I prefer plain back but that is because don't ride. Those gussets and underarm footballs are propably useful when reaching handlebars..
@jmo74: great looking Aero (corrected the brand), good fit!
This is why I didn't buy 141 or 641 after I tried it in the store. Great leathers, great classic design... but it is very bulky. Underarm footballs can be removed by Schott but they don't really slim it down (it might just allow you to squeeze into 1 size smaller). It's the heavy and thick leather and gussets. I didn't like 654 leather after trying naked cowhide on 141. Also it doesn't have the buckles, which I kind of like.