What is it you're lacking from the 360? I havent used one but looking at the specs you will gain some power with the 430, also the 430 can be set to lower power in manual and you could use it as a slave if you were to get a 580 or ST-E2 but with cheap radio triggers available that wouldnt be a priority for me. The main difference seems to be that the 360 is TTL not e-TTL II, so you may notice an improvement in metering although I've never compared TTL and eTTL II so dont know if there'd be much difference.
If you were thinking of adding another flash I'd recommend the 430 but I'm not sure I'd swap the 360 for the 430 unless you can identify what it is you want to improve.