I saw a topic in the VDMSound forums talking about the commercial alternative to VDMSound but I couldn't post a reply since the forum looks to be closed.
Seems like an interesting application, however the OPL implementation seems to be fairly broken or otherwise substandard compared to current offerings.

http://www.softsystem.co.uk/products/soundfx.htm (source code link at the bottom of page)

I dunno, it seems interesting but was wondering if anyone familiar with VDMSound might want to give this another look and their thoughts?