I like Florida's playbook too. Seems pretty realistic, and is is also diverse.
I don't use other playbooks so I can't speak as to whether they are as well-rounded as they should be. But as to the point of many plays being very similar in terms of the pass routes, that is a good thing IMO. That is how football works, you have a couple of basic concepts and then you make minor tweaks to take advantage of what the defense is doing.
As for playbooks I have faced in online play, I haven't gone against any that really gave me trouble. There was one guy with USC whose passing game I just could not stop, he used the passing cone and kept firing high passes to his outside receivers and I could not stop it. I also only faced one guy who played Florida and exclusively used the Gator Shotgun formation. I couldn't really stop him, but on the other hand I think it's difficult any time you face something that you haven't dealt with before. With just the one formation and all of his audibles being for that formation, I could never tell if he was going to run or pass, inside or outside. To me that is what makes an opponent difficult to defend, if they are balanced between the pass, the inside run, and the outside run. My skills at controlling defenders to make tackles in the open field are pretty bad, so generally on defense I am relying on my ability to figure out the opponent's tendencies, and take them away with good defensive playcalling. The thing I like about defense NCAA 08 (on 360) vs NCAA 07 (on 360) is that on 08, if I know what the opponent is going to do, I can stop it. Whereas in 07, the QB contain AI was so bad, there wasn't a play on defense that could help.