It should be fine. I don't even think the Vita can region lock though I didn't realise the PS3 could before P4 Arena. If it is region locked it will be a first and nothing has been said.

Apart from the DLC restrictions and possibly the online I believe it will be fine.

Personally I'm getting impatiant with the US release date and the actual wait for it to arrive will be pretty unpleasant too. I'm at the tail end of a play through of the PS2 game and it's going to be hard not to start again imediately. So yeah wasn't going to wait for Febuary on this one.