I really like the D-4 and will be the owner of the newer DM5 module as well. I not only use it with my Synthesizer and sequencer rig but use its 12 triggers on my Acoustic Drum Kit. Now my Drums act as a controller too and I can record my performance into a sequencer or control my sampler or synths right from the heads of my Drums. The D-4 is very responsive to my playing (no time lags) and has good parameters to twick when you do use the 12 trigger inputs. It would be nice if the D-4 had an FX section but at least they did add the auxilary outputs. Bottom line on this unit: It is not a drum machine, it has very few editable paramaters (ie. no Filters, Envelopes, FX etc.). Makes a great sound source for more demanding drum tracks (not like some of those cheezy general midi drum sounds offer) by having a wide range of sounds and can be used by Drummers and Synthesist/keyboard players alike.
Comments About the Sounds:
There are many Kicks, snares, toms, cymbals, Misc. Percussion and sound FX. The Effects in the unit are a part of its sample Rom. The Hi-hats, esp. the opened ones, in my opinion are weak. They are to sterile, same sound only its volume changes has you hit it. The newer DM5 has a random sample play back feature which should be the cure I'm looking for.