I got the Titan D200 a couple of months ago but really got a chance to try it out in Bonaire a couple of weeks ago as well. Actually, Continental LOST my housing case so I actually got a chance to dive the Sea&Sea D200 housing as well.
First, the Sea&Sea D200 housing is a nice housing. Compact (compared to the titan), comfortable grips without gloves and not to heavy in the water. Controls are fairly easy to work and took little time getting used to. All in all a very nice housing.
As for the titan, I absolutely love it. The ability to control shutter speed, aperture, shutter release, focus lock and strobe power all with just 2 fingers is a breeze (without having to take your hand off the handles, but that may be a bit harder if you have smaller hands). As for the housing using the camera battery, I did not see an issue while doing (2) dives on a single battery charge, each dive 45-50 mins firing off an ample number of shots. I even used the same battery charge to download the 100+ RAW images to my laptop. Giving the size of the housing its pretty heavy on land and although heavy in the water..nothing a few buoyancy arms can't fix!
This is the first DSLR housing for me but I found out about a pretty nice feature due to a dome port coming off of an Aquatica housing in the rinse tank causing the loss of a D2X. On the L&M ports there is a nice little tab that helps prevent the ports from accidentally coming off. Seeing that the Aquatica's didn't have it, I took a look at the Sea&Sea and noticed its not on their housing as well.
I'm curious if Subal does or does not have this feature. Though I know its certainly not a deal breaker, I know the nice guy who lost his D2X would have liked to have it!