for the drums i send the MIDI Out to my SP-404, where each D2 MIDI note triggers the SP's samples. I have placed my samples in line with how the D2 groups drum sounds, to enable the D2's drum mutes to still function despite the sounds being outboard.
the bassline i send out to my MC-09, where with a few tweaks it can go from rumbling bass to pure acid and back again.
so, the D2 has the MC-505 engine in it;
but not the ability to access all those parameters via its own interface
all main LFO and Envelope stuff is of course doable, similar to MC-09 patch writing but a bit more involved and more options
check these jpgs, they have a layout of all the parameters you can access via MIDI, using the editor to craft a patch of the more detailed stuff


what i've been doing is writing patches in the machine, then later on when i'm through jamming, accessing the patch i saved and doing a bit more fine work on it, choosing key following settings, messing the velocity of the Res (can make things bounce very acid-like to have the res oscillating in sync with how hard you hit the note) and doing some EQ work to sit the tone right
the D2 looks like a toy, but inside it hides an amazingly capable beast!
here is a quick idea of how the D2 sounds...all synths = D2 except Bassline = MC-09 and drums = SP-404
http://soundcloud.com/drewzle/drewzle-u55-jive
this is a recording of a live jam, and is pretty raw...but it gives you an idea of the sort of tones you can get from the D2. they do get a bit Res'y in places as i mess with the X/Y