In most of the games i played on PC, you had to switch to the grenade to use it, so i never did. Isn't worth the risk of putting away my gun. I actually use them if you can just press a button to throw one, but I get along just fine with no nades at all.
lol, it's funny you say that, because there was a LONG discussion on the SD boards, about how they wish there was an option to use nades the old way, like in W:ET.