Hi. Yeah, it's cold, but it's some good diving; good enough I flew out last August and caught
a Truth Aquatics limited load live-aboard trip to the Channel Islands after doing
some research into the California dive scene. In exchange for the exposure protection/cold water hassles, you get kelp, sea lions, harbor seals and other distinctive wildlife.
The California dive scene can also offer greater diving freedom (e.g.: more liberal solo diving tolerance) by some providers, and some cheap live-aboard trips where you can cram in a lot of diving. Granted, such don't have all the amenities of some Caribbean live-aboads, but to me it's kind of like do you drive a Honda Accord or a Lexus? I've enjoyed a couple of Caribbean live-aboard a lot; just adjust your expectations to your market and I think you'll be pleased either way.
All that said, I imagine you'll get around to a warm water trip sometime. It does have its advantages...
Richard.