The short of it is I bought the UDD primarily because one of my vacuums has the boom arm fitted, which made it a real hassle to get the motor housing off and back on when changing a bag. This is now a lot easier.
I've had no issues with static electricity so far.
Although suction is diminished a bit due to the Dust Deputy, it stays constant because the bag inside the vacuum doesn't fill up (eventually the pores in the bag will clog and cause suction to diminish, but it's going to take a very long time and/or a lot of vacuuming before that happens)
I've found the suction of a CT vac tends to drop off once your bag starts filling up. This is also less of a problem with the Dust Deputy.
The only problem I have with the Dust Deputy is that it makes any vacuum a big unwieldy contraption.
I can recommend the Dust Deputy to anyone who has a boom arm fitted to his setup. The boom arm negates any compactness of your vacuum. Adding a Dust Deputy doesn't change that much, but it does make it significantly easier to do bag changes.
If I didn't have a boom arm assembly, I probably wouldn't have bothered with a Dust Deputy though.
Below is a quick video showing how well the seperation works on my setup.
