This is a GREAT thread!!~
I have only a little bit of knowledge because I tend to stick with only a few leathers. However, in terms of "chevre" , I have found that there is degrees of slouching depending on the type of chevre, obviously. My Chevre de Coromandel 35cms. really do not slouch, they maintain their shape well. The Chevre Mysore does slouch a bit more, forming a bit of batwing, only slightly. The most prominent slouch, and this is obvious, (but I just experienced this myself for the first time), is with the Chevre de Coromandel Souple in a Birkin, really is 'souple' and will slouch a little upon use all the while maintaining the general Chevre shape ---- so it is a very different. I love all 3 of these skins, with the regular ole CdC being my favorite, and it is the one that maintains its shape the best out of these 3 types.