I dont mess witht hem in rolling because i think the wrist is nothing you want to hurt on a training partner. The wrists when used to sub is normaly snatched and done quickly not giving the opponent much time to tap, and also some times making it unable for them to tap..
If you break a mans wrists or just injure it one good time, he could be out of the sport and alot of other things for a very long time. Wrsits dont heal so easy and there is so much that could go seriously wrong requiring surgery to fix.
If you know them great, but i dont like to make them part of my practice in bjj. I want to be able to train every day, twice a day even.. As hard as I can. Throw wristlocks into a daily occurence now all the sudden you are to injured to train so often.
I tap as soon as possible when people reach for them, just so i can keep training and not have to worry about messing up my wrist. Just last week it happened and i had to wear a wrist brace for a week. It still hurts to post on that side.