I shoot a Canon 6D above the surface (not quite brave enough to take it under water, so I recently got a Sony A6000 for underwater). Have you considered a Nauticam Housing? They are in the same basic price range as the Sea&Sea, but I find their housings very ergonomic.
Having said that, I have used an Ikelite housing for a DSLR (Canon 20D) before and while it offered excellent protection, I found it to be big, bulky, awkward and heavy. It was, however, a very economical housing.
Both the S&S and the Nauticam housings will cost significantly more, but they will be lighter, smaller have have better ergonomics.
The other thing to consider is what lens do you plan to use. (The Tokina 10-17 fisheye is a great U/W lens as is the 60mm macro.) Make sure that whatever housing you plan to go with will have ports to support your choice of lenses.
If money is the critical factor, then your choice is clear (so to speak), the Ikelite costs much less. If however you can afford one of the other housings, then I would opt for them instead because of the size & ergos.
