Sorry for not responding sooner, I was having computer troubles over the last week or so.
I'm not sure if I'd call them common, but the last 2 or 3 years they have been hanging around the beach. There were 3 of them last year, they seemed to stick around pretty much the whole season, hanging around the same spots. This year I actually don't remember seeing one.
I do know that some divers have decided they need to "rescue" the fish that come to the beach, and armed with burp guns they take them. Personally I'm not a big fan. Yes, they'll probably die in the cold weather, but until that time, why not let them be for all to see?
My favorite was the diver who loaded his pneumatic spear gun on land, walked into the water, shot a big trigger fish, came up and said "can I eat this"?
I was in the water last weekend, and I read 55F at the bottom. Chilly, but manageable.
Nitrox won't help too much at the beach, but because it is such an easy dive, it's a great place to try out all your new gear, learn a tech setup, etc.
-Dustin