I'd advise you to get some sort of sampler, or maybe a software sequencer and a softsampler. As for your Roland, it depends on how much you like it. I looked it up and it seemed pretty cheesy, but if you like it and use it, then keep it. With a sampler, you could always sample stuff from your synth and the mess it up real nice.
Personally, I avoid drum machines. I prefer to use sampled drum sounds that I can manipulate to my heart's content.
For experimental, industrial, and dark stuff, out of the box sounds tend to not cut it. DIY is a major part of the industrial and experimental asthetic.