Basically - you need both! Simple as! You'll end up an NS whore like everyone else (me included)
Neither is too anything!
The Evo is the perfect amount soft for jibs and pressing the shit out of and buttery heaven!!!!!
The Proto is the perfect amount stiff for carving (for a mid flex true twin mind!) and for landing jumps.
The proto is NOT a stiff board and you can still butter like there's no tomorrow - just the Evo is the most playful board on the planet (don't quote me on that - I'm sure Nivek and Angry would disagree - probably with good cause - but that said there are a HELL of a lot of good reviews for the Proto and Evo '12)
You won't need another board for a while! .... (unless you find you want something for absolutely ripping the piste up like the Raptor or something to float on endless powder)