I've seen enough 20+ year old pairs of White's boots with rubber soles to think that the tales of rot are bunk. My own shoes with different types of rubber shoes seem to be doing as well as my leather soled shoes.
I haven't noticed much in the way of stretching for my Vibergs. Maybe it's the thickness of the leather, or the lining mitigated it. I'm also not sure if Viberg pre-stretches anything. I know Nicholas Hollows does that for his CXL belts.
Summoning DW on this one (and whoever else has an opinion on it, of course). Could there be any advantage to using a fiberboard insole on a Blake-rapid constructed boot? Kyle Rancourt has been posting on Reddit about using fiberboard insoles on their Blake-rapid constructed boots. It sounds like marketing nonsense to me, and I'd imagine that leather insoles are quite a bit more expensive. Is it at all possible that it's not?
CXL is also cowhide. White's CXL won't do it as readily, but it can still be a crapshoot. I think Wolverine and OSB use lower quality CXL, and so you'll see the awful-looking creasing. I haven't noticed these on my Vibergs, or as much as in the White's CXL pictures out there. Alden seems to do it much less, but it happens occasionally.