Last time I was at Pt Lobos I spoke with a team trying the Sevlor 2 diver diveyaks out They liked it, it won't win a race, but was significantly better than the long surface swim out of the cove. Since then I have been seriously considering the Sevlor but it will be primarily for Lobos diving to get me out of the cove to Granite Point or to Bluefish, or to Mmetridian Ffield from Breakwater.
My current thinking is that for most of the typical shore diving in and around Monterey and Carmel (exluding North Monestery -- which I wouldn't touch with a kayak) the Sevlor's are very cost effective alternatives to a long surface swim.
If you were diving in Maui, or Florida where 1-2 mile paddles are common to dive sites, then the OK or Cobra's would be perfect (have you noticed that all the OKs on Ebay are being sold from FL) but the reality in NorCal is that if you paddle a mile off shore you are in 3000 feet of water.
So, if you are planning on this primarily/ exclusively for a beach diving platform from Monterey / Carmel sites, where the typical paddle out is 100-200 yds, these should be fine....
That said, I haven't bought yet. I am still trying to decide between this
2 man dive yak
or 2 of these (my dive buddy is my son, so everything is in twos)
Sea Doo DPV
either will accomplish my goal, but in very different ways.
Good luck, and tell us what you decide.
Rob