Blind Diver--
Summing this all up.....
Macro or Wide--As Alex says, you need better vision for macro. Is your vision good enough even with a magnifier for macro? And do you want to shoot serious macro? If the answer is yes then find out if Backscatter can mount a viewfinder on the Ikelite housing. If Backscatter can NOT then rule out the Ikelite. In either case a magnifying viewfinder will add $900USD to the overall cost. Can you afford that cost plus a 60mm lens and still afford an aluminum housing that can use your INON S2000 strobe?
I think you need those answers before proceeding.
Looking at your pictures I think you'll prefer wide angle and fish portrates. Macro requires sharp eyes to find the little critters and quick hand-eye coordination to hit the shutter when the critter is in the exact pose you want. My eyesight is corrected 20-20 and I still have trouble with this even using autofocus.
Regards,
Tom