I personally have always used canon, 7d is a nice body. Do you need a full frame body, or just want to try it out? I know you said budget is no problem, but a cheaper alternative to a d4 is the d800. Greater resolution, effectively the same size sensor (thats the bit that counts, contrary to popular opinion). Downside being not as good low light performance, dynamic range, and noise at high iso.
Shameless of me i know.... but... How much do you want for your 7d and lenses if you decide to sell?