In general do Canon UW-users normally house the xxxD line of cameras or more often the xxD or xD? I do use Canon 500D topside now, but when moving into DSLR for UW use, the complete system cost is relatively so much bigger than the camera itself, so the cost of moving up to a xxD or xD is realtively small. Likewise the compact size advantage is largely lost when put into a housing and especially low-cost husings like Ikelite.
Worth waiting for the 70D or 7D successor?
In my case I was choosing between a 7D or T2i system. The 7D body cost about $1000 more than a T2i and the Nauticam 7D housing costs about $800 more than the T2i housing. Therefore it was an $1800 price difference. I opted for the T2i system. Which I have been completely happy with.