Why not just bite the bullet, save up the extra and get a Korg Triton with Moss board expansion- you'll get better sounds and fx out of the box than the other 2 and a super powerful VA physical modelling synth as well as a full function sampler, sequencer, 2 arpeggiators and analogue inputs so you can use it also as a super fx unit.

However, if you are only deciding between the Xp60 and N364, I'd also get the XP60. It offers more for the money, has a better sequencer, and you can expand with your choice of expansion boards (I'd start off with the session board to get a super excellent piano sound!!).

Also, a Korg Trinity at a good price (they are older now being replaced by the Triton) is also very much worth checking out. It's biggest limitation is the 32 note polyphony but this didn't really get in my way either when I owned one.