I
asked a similar question about cuff dump valves not too long ago as I had just recently purchased a Norther Diver drysuit at a smoking price and really didn't care where or what the exhaust valve was. I recently finally had the chance to dive it. Turns out it works perfectly fine. It is true that it takes more motion to vent. However, I've also found that the more drysuit diving you do the less you actually have to even use the vent. The non-adjustability of a cuff dump is not an issue as I'm always wide open on my shoulder dumps anyway (I'm a convert
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
).
One thing you might consider as well is that it might be a little harder to vent all the air on the surface prior to your decent. You might have to become extra diligent about burping your suit pre-dive. Or you might just keep your shoulder valve wide open at the surface and - if you can and want to - close it during the dive.
EDIT: I should add that I always use by BCD at the surface for buoyancy. It's my experience that when you're in a vertical position and you're using your drysuit as a buoyancy device at the surface, there is a lot of pressure that builds up at the neck seal. Air easily escapes when you are bobbing up and down in the ocean, causing 'waves' of pressure at the neck seal that eventually undermines the buoyancy of the suit.