TomC, How do you find the twin z240's go? I was looking at these as well with the Aquatica. How negative is the rig in the water? Are you using floats?
Oh, and did you go with the 8" done, or the 9." mega dome?
Inon Z-240 strobes: A real pleasure to own. I switched from DS-125 strobes at the same time I changed housings and have not found them lacking in any way. Usually, I leave the strobes set at approximately 3/4 power for w/a and less for macro, consequently I have not experienced any recycle time objections. I have found that when I use a lens that allows me to get close to a subject, either w/a or macro, the Inon strobes are more than sufficient; in fact, less powerful strobes would probably work OK. They are great for travel and the battery issue is a big plus for me as all my dive lights also take AA batteries. I own one fast charger and a bunch of batteries.
Floats: I just ordered my first set of Stix floats after handling a buddy's rig. I will get a chance to use them in Nov. My rig is negative; that has not bothered me but I imagine that improvements could be made in this area.
Dome Port: I have the 8" dome and a 6" dome. I really like the 6" dome as it is smaller and easier for travel. (You may have noticed, I am into a more travel friendly setup.) However, I will take the 8" dome with me to Raja Ampat in Nov. and leave the 6" dome at home. I see all the fantastic wide angle, over/under and under/over shots from that area and think that the larger dome will be better for this type of photography. I am not extremely well versed in this regard but I imagine that the mega dome might be more applicable to a full frame camera than a camera with a cropped sensor.