from what I've heard, so far it's impossible because the bootloader is locked. I've been waiting on someone to figure it out. and no, it wouldn't be the same, there are major differences between the two that would most likely cause a brick if you tried.

 

The bootloader is locked, but with the appropriate kernel/bootloader combo, it is possible to use Odin to unlock it long enough to flash whatever rom you want. The most typical Bootloader those roms use is ClockworkMod so you'll be guaranteed consistency from then on.