Well, the Boog just arrived a little while ago. I haven't had a chance to fire it up yet; just take it out of the box and look it over. Physically it's a bit wider and significantly taller than my Roland Boutique synth modules (I have a TB-03 and a pair of JX-03's), but it's really not all that dissimilar. There's a bit more room on the Model D's top panel, and there's a decent amount of space around the controls so you can actually get to them fairly easily without hitting something you didn't intend to. Then again, I don't think the control density on the JX-03 is all that bad either, so YMMV.
There's a much better selection of patch points available on it than the Boutiques have too, and they even threw in a couple of 1/8" patch cables, as well as what looks to be a roughly 1' long ribbon cable - I'm not sure what that's about. I guess I'll have to RT(F)M to find out.
The external build quality looks a bit better than I expected, and all of the knobs and switches seem to be pretty sturdy, without any wobble or other weirdness. So far, so good!
I'll try to fire it up and give it a listen later tonight...