Thanks for the excellent feedback, guys. Some of the most helpful I have had, and I agree with much of it.
There are a few points I will answer for the sake of debate, not argument.
Rand and Giles both mention that the divers are a bit small in the frame, and in some shots are lost in the background. I agree that this is a problem in these small screen images, but this problem really tends to go away when the images are viewed/printed larger. Also I have shots from the each of the setups with the diver larger - but I prefer the ones shown here.
You also both touch on the dressing and posing of models. These were conscious choices.
One of my main aims when photographing people underwater is to make them real individuals rather than the generic model. I do not like an overly posed look in the images - I prefer the model swimming through the frame - rather than stuck on with legs perfectly together. I guess there is a trade of between neatness and naturalness, here. Clothing also has a similar trade off, and I am a big fan of divers looking like real divers. So NO 1970s big oval masks, NO 1980s pink wetsuits and NO weird dive gear without all the normal hoses and a normal BC. I like to shoot real divers (although I accept that there is a difference in taste between N.American and European Editors in this regard). I take the point about the bikini bottoms - which I agree are fine for snorkelling - but I don't know a regular female diver who when not wearing a wetsuit will dive in bikini bottoms over shorts. Maybe I know the wrong girls! But again it is a trade off between fantasy and reality.
Negative space. Definitely up for debate. Many of these shots are taken with due care to negative space as this increases their ease of use editorially. Many of the diver verticals have plenty of space for cover titles and words etc.
Giles also raises the point about cameras. I chose to do a lot of model shots with cameras for several reasons. First nearly all divers carry them these days, (second to justify to the taxman why I needed the S3!), also I often need illustrations for photographic articles and finally and probably most importantly it helps build the model's character in the shot. Gives them a sense of purpose and gives the final image a stronger story. As for eyelines. Yep the plan was for the diver either to look at the LCD screen or the subject. Which I think is the case in most of them.
I do agree with Steve on his comments on my lighting. This is exactly the direction I want to try and go this year. But I do want to continue to take the clean, bright shots that are recognisably mine. I guess I want to be a bit more creative 5-10% of the time.
I agree with your comments on Doubilet's stingrays. It is pretty difficult to make your pictures different from his when you are in waist deep water with a fisheye. But for what it is worth I have always tried to shoot bright, punchy images of the rays. DD's images have always been more moody (and better).
Also when I first started shooting B&W shots of the rays, including the one that is on the front of my website, I had not seen anyone publish BW ones (although they undoubtedly had taken them).
Anyway on this trip, I was influenced my Jim Brandenberg's use of light I decided to try more creative lighting with the rays. Shooting much more across and into the light. But as a result I do think that my recent efforts look more like DD's than my older shots. I guess this is because DD and JB are both masters of light - and by trying to emulate JB my images end up looking like DD's. Back to square one, I think.
Anyway I really do appreciate all of your insightful comments. It is hard work this UW thing...
Alex