I used the Ike housing with a Canon G11. It is a good functional housing. It also accepted a macro wet lens which was really helpful. The macro on the G11 only works on the wide angle setting which means you have to be so very close that macro sort of ceases to have much meaning.
The problem my set up had was the widest functional wide angle I had was 35 mm full frame DSLR. It said 28 mm but with the water refraction, there is an adjustment. I found with large subjects such as turtles, stingrays, dive buddies, etc, I needed a wider setting to get good functionality. Long range in underwater shooting is 5' and you really should be closer. The lack of a serious wide angle (20 mm or shorter) became more and more vexing as I gained experience. Of course, if you want to shoot only medium sized fish and macro subjects, you will not need a wide angle. So I don't know what your needs are.
The TTL capability is something that is pushed but I found it not that useful. I soon went to full manual setting. A ranging shot would give me my needed exposure. I could adjust iso, strobe position or strobe setting to compensate. The area where TTL would have really been nice was in a spot where it was no help at all. If you are shooting at something on a sand bed like a stingray or a jawfish, you get a bunch of light bouncing back into the camera giving you horrendous over exposure. The TTL does not compensate for that. At least, not in my experience.
As far as strobes, I like the 160 and the 125 for my DSLR. But I did pretty well with a pair of 51s for my G11. I feel having 2 strobes gives you more control over lighting. Having two also tends to greatly reduce that terrible shadows you can get from one strobe. The 160 and 125 have better batteries though. On the downside, they are large and tend to be far more cumbersome.