Hey, Jeremy, long time no see!TrojanCatMan:I plan on using the internal flash initially (save up money first). Is this flash block a common to Ikelite housings?
How do you like the SD900? Looks very slick... I'm jealous, for those times when a fully auto P&S does everything I need! (many times, it really does) I'm curious why you went with the sd900 vs. the wide angle and image stab. on the sd800? MP envy?
Anyway, as you may recall, I have the Ike housing for my (new) S80, and using the diffuser I don't have any problems with blocked internal flash, so it's not all housings. I did the same thing and used internal flash only until I got my strobe relatively recently. The Ike housing is seriously heavy duty, but it really makes for a chunk of gear... you'll never forget you're holding a big honkin' camera.
Anyway, my advise, for you, in this situation, is to get the Canon housing. It's MUCH more portable, and should you reach the point of wanting add-on lenses and the works, you'll probably want a new camera with more manual controls anyway. Since you're using a full auto camera (in UW mode), you may as well take advantage of the super small and handy size of the Canon housing, and save the Ikelite housing for a camera with more serious manual controls. Since you're talking about optical firing anyway, you should be able to add a strobe to the Canon housing at some point if you really want to.