EDIT 7/12/16: A couple of new, relatively small mods have been added.
The mod all up didn't take too long, about 3-4 hours starting from bone stock all the way to completely finished and closed up. Performance overall is pretty good. I'm getting typical Worker flywheel muzzle velocities, anywhere from ~110fps with bad darts to 140fps+ with really good darts on a good shot. Spin-up time is short, nearly as fast as the Hellcat builds I have. Flywheel noise is very harmonious and reserved, I'm getting a lot less vibration than most of my other builds, including my Bullpup RS with the Artifact red cage. Accuracy is fairly good, certainly more than usable for my purposes, and the trigger pull is quite smooth.
All round I'm quite happy how the Desolator turned out.
I added in a dart guide made from cardboard, toothpicks and hot glue, very similar to that in my Rapid Red. It's not perfect, it would naturally be much prettier and sturdier if made from plastic, but it will do for now at least.
I also looked at replacing the mag release with a Worker Stryfe lever, as I find the Desolator's one to be a bit awkward. A little internal clearing needs to be done, but that's easily done in a few minutes with a blade/pliers/other tool of choice. The Worker Stryfe mag release is a little loose on the screw post, but once closed up it works nicely, much more comfortable than the stock mag release.