This is a temporary solutiuon. I have someone that is going to make me a custom housing for the Mk2s that I have. sorry, don't even bother asking. It is a favor to me, limited productions 
As for this EWA-Marine. Make sure you buy a weights for it. Not the internal one, as it doesn't fit with the mk2s. You have to get the external.
My first dive to The Sea Tiger (120ft), the camera locked up, because I didn't have enough air in it. I wasn't about to start blowing air in to it. Since I have $8k just in the bag.
My 2nd dive to the pipes at night, it was 45ft, and it was a little bit positive.
Than the Corsair, which I got enough air @ depth of 105ft so it was neutral. However during the ascent, it was like a balloon. So unless you are totally comfortable with your bouyancy. I would suggest not using the bag. During descent you have to ride it like a horse, or drag it down like a little b#$#h.
Also, pretty much all the controls is USELESS at 60ft+ I couldn't turn the dials. Everything is shot in AV mode, at f/5 I tried turning the knob, but it takes so much effort you start to burn air.\
Also, because of the compression from the bag, my 580EX was pushed pretty hard so it was in "Bounce flash" mode. I guess it works out okay. I need to try to see if the 14mm panel help spread the light more.
I dove with both the 24-105mm IS and the 16-35mm. at 24 it is bad. Vignetting and soft side (need dome port). I won't even both with 16-24.... Also... because of the pressure, zoom is useless. And you need a lens that has internal focusing.
Usage note. For whatever reason... nothing through the viewfinder was in focus.... It might be the plastic + air... but I couldn't tell... however if you are able to get the bag right, you should be able to use the AF system. You'll have to learn how to use both eyes to composition your shot, and trust your AF system.
Final note, during descent. Make sure you hold the lens port against your lens. If you don't during compression it will set in the wrong way.