The 320 is very good in subplaning. The 380 long boards will always be better for straight line subplaning speed. If you are not racing, then the 320 is more fun to sail because of easier turning and added stability and earlier planning.
I haven't sailed The Kona One. I think doesn't offer the same performance since it doesn't have as big a centreboard and no adjustable mast track.
I have owned the 2009 and 2011 Phantom 320. I think the 2011 is much the same as the current model. The 2009 is the easiest to sail and the 2011 is the faster of the two.