Hey all, long time lurker, first time poster
My S320 is currently my favorite.. I may have lucked out but the one I got was set up great, plays like a dream. It made me fall in love with the Saber models. I ended up also picking up a S470 later, but that one was assembled by a drunk, so I'm in the process of giving it a full rebuild. Point being, look for a well setup example, from what I've seen some are well built, some may be slapped together.
Anyway, on the S320, for me the lack of fretboard inlays actually improved my playing.
The ZR trem is cool too. I'm was normally a hardtail guy and had given up trems a while ago - too much hassle for how much I actually use them - but the ZR is very stable and the ZPS suits my style well. You may not like the ZR feel if you're used to standard Floyd Rose types, but I find it smooth as butter.
And the finish isn't my favorite, but compared to the S420 it seems a bit lighter and better balanced.. I'm thinking the lack of a thick lacquer makes a subtle weight difference.
My only gripe on the S320 would be the pickups - good, but not great, they will be getting swapped out. But that can be said about a lot of stock factory pickups.
I say do it, but hopefully you can try in person before you buy. The one I snagged is the easiest playing guitar for me that I've run into.. but now I'm a Saber junkie :P