ileiman

I have owned and dived two years with the Ikelite housing for Canon 7D, and have used the Ikelite 8 inch dome on +100 dives.
I have never had any issues or serious concerns with the dome. Never had any leaks either.
With the Tokina fisheye the dome port body is extremely short, and in fact attached in a bayonet fashion. You don't get to see too well how the o-ring seals, but the whole package seems quite rigid and reasonable external forces will not dislocate the port.
With the Sigma 17-70mm zoom I use a longer port body, which may appear to make the assembly more susceptible to external forces, however I have not had any issues with that either, and have taken the camera to some really rough places. Using the longer body allows you too see very well that the seal is OK.
Picture of the whole rig with the Sigma 17-70 below:

And underwater:

Recently got the Canon 7D so I am still learning it.  What is the recommended flash unit that one would purchase for  topside photo work?  
Steve

I have a Canon 430EX-II. I really like it. It is almost as powerful as the more expensive 580, and has all the features I need.
When attached to the camera you can tilt and swivel it to gain better lighting. It can focus to a fairly long distance  when using tele.
For close-ups, a useful accessory is a "bounce" which softens and diffuses light.

You can use the 430EX-II also as a remote-controlled flash with the 7D. This is a really cool feature and allows you to get really creative.

read this topic
plenty of info there.
acrylic dome is easy to repair

I use Hagor 100 liter soldier's kitbags. The bag itself is 1 kg (2 lbs), and I can easily fit all my dive and travel gear into one bag that weighs 16 kg (35 lbs). You can carry the bag as a rucksack and it take really rough handling. It is also very cheap at under 70 EUR (used army surplus even cheaper), available both in black and green. I have used these bags on many really long and rough trips and they are still in good condition.

Here is a link to Hagor's web page:
http://www.hagor.com...C...3&BSP=12188

Here's a shop in Finland that sells them for 69 EUR:
http://www.varustele...usta/_2IL0Y6NL8

Does anyone else have this housing? How do you like it so far? I just purchased one and have mixed opinions about it. I really do not care how the dome port attaches to the housing. Would love to hear what others have to say about it.

I have dived for over a year now with the Ikelite housing and Canon 7D. I have done two long live aboard trips in tropical waters (Indonesia and Red Sea), and lots of local dives in the Baltic Sea. A total of 100 logged open water dives, plus numerous test and training dives at pool.

It works and seems to be reliable as long as you take good care of it.
Comparing to anything else, I especially like the price of it. While even the Ikelite housing with ports isn't exactly cheap, all the others (Subal, Sea&Sea, Nauticam, Aquatica, Hugyfot) are ridiculously more expensive, and I really cannot find much justification into spending 2x or 3x the amount of money to a housing. Maybe Ikelite isn't as cool & nice as a Subal, but hey - look at the prices  

What I don't like about the Ikelite is the weight and size of it on land, but below surface it doesn't matter if you use floats. Also the controls could be a little smoother to use, but you can live with that. There is no control for the joystick, which I miss a little, but you can live with that too. Also I don't like the idea of having to disassemble the whole system just to swap the camera battery and memory card, but you can live with that too - and in any case the battery typically lasts up to four one hour dives (= an entire day of diving).

Almost forgot: on my housing the live-view lever broke, but Ikelite repaired that for free under warranty, and changed it to an ordinary push-button, which I think works much better.

I strongly recommend changing the Ikelite arms to Stix arms with floats. That allows you to make your rig neutrally buoyant and well balanced under water. I also use Ikelite DS161 strobes, and those are very good & powerful strobes but unfortunately very heavy as well. The regular Ikelite arms are also too short for wide angle work.