not really. feels pretty solid. i think i will try and diy some stuff to hold the lens from the bottom.
Ya, you should really get some sort of mounting plate and a pair of rods under the camera, then under the adapter mount some sort of support onto the iris rods. I'd also want a support under that lens. In fact I am pretty sure that it's bending downward visibly in the picture.
RE: Adapters dropping in price - maybe somewhat, but don't expect people to start discarding them like bad paper. Don't get me wrong, I LIKE DSLRs, but jello sensor AND crap on crap h.264 line skippy crap-pression they've got a tad bit of catching up to do. Honestly, jello sensor bothers me less than using a delivery compression standard at the time of image capture.
Folks often forget the true cost of rigging a DSLR for proper motion picture shooting. I've done several days of shooting on the 5D. One project the DP was just trying to use the camera as it was. Making handheld extremely shakey with the comparatively small body. This also had the effect of the camera being too lightweight to mount on the steady cam we had (very small glidecam) AND made it fundamentally impossible to pull focus. Any adjustment on the lens appeared as camera shake.
In contrast, I did another 5d shoot where we rigged the camera onto a proper plate with iris rods, follow focus, matte box, etc etc etc. Of course doing so can more than DOUBLE the cost of the camera body. Granted, it makes for something pretty lightweight by comparison to other rigs but once you get a decent Marshall with battery on there, a big fat 200mm lens, and the associated support gear it weighs about the same as a fully rigged EX1. (which I also shoot frequently)
Then of course there are lenses. f3.5 DSLR lenses aren't too bad in terms of price, but if you want any of the faster nicer glass from canon (like f2.8 primes, or heaven forbid a fast L series zoom with IS - does that even exist?) then things get really spendy.
Again, I was actually pleased with the results we got on the 5D shoot (aside from the compression scheme which I will never, ever, ever stop hating when used as an acquisition format) when the camera was properly rigged for shooting video. The issue is that doing so is expensive. You *can* shoot DSLR without all the bits, but having done it both ways I'll say the results are superior when you do.
Edit: I also forgot that pulling focus on DSLR lenses is sort of annoying. Most of them have noticeable breathing and the gear rings do not have a hard stop at each end of the focus range - meaning it is possible to spin the ring past infinity, for example, which doesn't change the focus once you pass that point, but it WILL screw up your marks.
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Now, for the indie shooter most of this is academic - but it isn't indie shooters (by and large) who have loads of Letus and P+S Techniks sitting around begging to be swapped for DSLRs. If I had that gear, I'd probably keep it and *add* a DSLR to my kit rather than replacing my adapter.
Funny, the more I work with my camera, the more I am removing the "helpful" things, face tracking, flip screen lighting, autofocus. There's a "pro" setting, which allows me to play with more. 
