3-4 Defense Seems like the biggest downside to the 3-4 in college right now is that the NG is a tough spot to recruit. Your competitors will tell kids that they will hate playing NG in the 3-4, and even though most of the top NFL defenses use the 3-4 or some variation of it, they'll probably tell kids that the 3-4 hurts them in getting ready for the NFL.
Terry, Yep, you hit it on the head. When the Wrecking Crew was running roughshod over teams back in the 90's, we used the 3-4. Very easy to recruit LB's to it, and not too bad for DE's... but finding that guy who is willing and able to take on a double or triple team EVERY down is hard. And there will be TONS of negative recruiting as you mentioned. Back then, most NFL teams were running 4-3 so it might not be as bad these days... I'm happy to be seeing the return at Kyle!!
The Gators use the 3 - 4 a lot. There was some speculation that we would switch to it as the base formation, but that hasn't happened.