I just put in an order for the Subal C10 Housing for my 10D. My main reason for doing this is because I have all the Subal ports already. Even if I chose to go with the cheaper Jonah route, by the time I add up the Jonah ports, I won't be as far off from the Subal, and I won't have to change zoom gears or carry 2 sets of ports/housings (I'm keeping my film Subal for when I need the 16-35L at it's full 16mm)
I've seen the build quality of Subal, Ikelite, S&S's new plastic housing and Nexus. I wasn't too impressed with the S&S one and I've known a couple of people who've had problems with them. Ike doesn't have a 10D housing yet and Nexus doesn't make one for the Canons....so Subal was my choice.
As far as ports are concerned (dome or flat) it depends on the lens you want to use, and unless you're using a lens on the ends of the focal length spectrum, you'll be well served by a 6" dome and a flat port for the 50macro and the proper extension to use the 100mm macro. I use the following underwater: 16-35L (DP-SWC with 40mm extension and +4 diopter), EF28-105 zoom (my hunting lens, used either behind the DP-SWC dome port with diopter or the FP90 flat port), EF 50mm macro, behind the FP94 and finally the Tamron SP90mm macro behind the FP94 and a 50mm extension.
Stu