I can’t speak to the Pro Endurance, but I have a Wintec Pro AP and a Wintec Pro Dressage with contourbloc, both with CAIR. I haven’t had any problems with my horse and CAIR (yet?)-- my horse seems more comfortable than ever. But the Pro Endurance is available with flocking if you have the luxury of shopping around for one.
Also, I’ve heard this through the grapevine, but have not been able to substantiate it: supposedly the Wintec flocked panels are now made as inserts just like the CAIR panels are. Which means in theory, maybe they can be ordered from the manufacturer and swapped out more easily than in the past? I can say that the CAIR inserts will just slip out if you disassemble the saddle. Regardless, Wintec saddles can definitely be flocked by a saddler-- I have heard of many instances where that was done.
For what it’s worth, I like the contourbloc even more than I thought I would. Can’t speak to the rear thigh blocks. I feel equally secure in both my Wintec saddles. I really enjoy them.