MOTM

Here's my take on 300 vs. 310 VCOs.

Find a way to try both. Depending on the room you have in your system 
to devote to VCOs, I'd start with one or more 300s. The extra 
triangle and sine outputs are invaluable, not to mention linear FM 
and sync inputs. You really have a much wider tonal palette to 
synthesize from.

Once you have a couple of 300s, the 310s are great for getting a lot 
of bang for the panel space buck. They have a nifty variable saw to 
pulse output that the 300 doesn't.

Moe
http://www.hotrodmotm.com