Is it not wise to flash a ROM on system 1?

I mean whats the point of the having different systems anyway?

Also, the 650/650/300mb deal you suggested isnt enough at all, even with an SD card. Whats a more realistic # if i want to put music and a lot of apps on the phone. I never had a storage problem with my galaxy phones.

Right now im running SlimKat, i know that its a matter of opinion, but in YOUR opinion what do you think the best ROM is right now? Or your personal favorite.

Again, thanks for all the help man.