Ikelite has a link on its site to a review of the 5700. It is very thorough, and get's a "highly recommended" rating. So, I was on my way out to buy it, and read your post, Saltywater..... Oh, what to do!!!
If you go to Ikelite's website, they have a link on their Underwater Systems page "Photo Tips & Help". On this page there are several links, including links to outside reviews. I found this site very helpful:
http://www.dpreview.com/
It doesn't review necessarily for underwater use, but it's got some extremely thorough reviews. Another site listed, wetpixel.com, is geared toward UW use - if you search on it for Ikelite, you'll see a review for the 5000 - but if you click the link - it takes you to the review on the dpreview.com site.... doesn't go into the combination of the housing with the camera.... I didn't spend a lot of time looking around (I was on my way out the door to get my 5700... ), but this page on Ikelite's website has some useful links.
You make some good points about the housing....
HOWEVER, my decision is still swayed by the fact that I already have the DS-50 strobe - I just need to get the arm attachment for the housing, and sync cord for the 5700. In fact, I wonder if I could also use the MV also (2 strobes!!!), and slave the MV off the DS-50..... Hmmmmm.....
As noted, the built-in flash on the 5700 is blocked by the housing, and can't be used with a wireless slave.... So, a sync cord is necessary.
By the way - the 5700 does have an optional accessory battery pack that fits on the bottom of the camera kind of like a motor drive fits on an SLR. (back when they didn't have built-in motor drives....)
The battery pack takes regular AA batteries. Of course, I assume it doesn't fit into the housing with this attached... but this would be good for land excursions....
Well, I think I've done my due dilligence, and know what I'm getting into.... so.... here I go.....
Thanks, elshiznit, for starting the thread. It'll probably be next spring before I'll have the housing - we're doing a liveaboard in May - so I'll get the camera, learn to use it, get the housing in the spring, and do a couple of day dives with it before May. I'll let you know what I learn.