My only real need for a controller is to have an easy to use, big, lit button to Start/Stop/Pause a song for 2 decks. It's also nice to have a cue point or loop function. Other than that, I agree the laptop is just as easy for pitch, etc.
Well I still don't get the drift of the controller thing. Can't you find the F1 key on your keyboard. Even with my bad eyes, I can find it.
As far as a built in sound card on the controller, you are putting all yer eggs in one basket -- if your controller dies, so goes your sound output. You could have 5 lappys, but if your controller/mixer/sound device goes down -- you're SOL.
Logic would presume that you have redundancy on all links of your chain from input to output. So, you would need two mixer/controllers/soundcards, in order to have redundancy.
BTW, the F5 key, is just to the right of the F4 key -- amazing how they came up with that...