Yeah you could say it's what the Ddrum 5 would have been. I suppose the "5" in the name was in part a nod to fans of the Ddrum brand to spark interest. It certainly did with me which is what lead me to buy one.
As for chrome elite and the ddrum2 to trigger from your acoustic drums, I would have though the Ddrum4 was more equipped to do this as it's got proper acoustic trigger algorithms in the "trig" part. I triggered acoustic drums from a Ddrum4 in 2004 and had wonderful results, all apart from kick drum with a double pedal. Though I suspect if I had deadened the kick drum down with a pillow it would have been fine. But toms and snare were superb!
Plus, the Ddrum4 can send out 8 midi notes (if my memory serves me right) per channel, though this might be more if you're using the cast precision pads with position and pressure sensitivity.
Still a great module, 20 years on.