I go against the grain a little on this one personally, but then again, I'm not a hardcore stealther. That said, I've done my time, and I have both omnis and cards. In general, I prefer the sound of the cards just to cut out some of the ambient chit chat, focus the sound, and cut some of the boom in the room possibly. HOWEVER, I actually use omnis pretty much for all stealth these days, and the reason why is I find them to be a little more forgiving on the head movement/position -- move your head with cards and you'll know it, lol. With omnis you will too, but I feel they are more forgiving. And, if using your head as a baffle, the biaural sound you can get with omnis sometimes can be amazingly realistic.