Please don't get mad, but I'd really advise that you go out and at least try out the SRJV80-10 Bass & Drums expansion baord. It is really worth it.
At one time (a couple of week ago) after owning an XP50 (recently upgraded to an XP60), I got fed up with the drums in the XP. They sounded terrible when compared to a drum set - I should mention that I can also play the drums and it was frustrating.
I then went to my local music store and tried out the XV3080 and was blown away by the realism, and sought to find out if my XP could sound like that. It's kinda funny. I had a Hip-Hop expansion board and completely ignored the B&D board because of the lack of variety (just bass and drums).
When I actually went toi try it, I was blown away. These drums are the best things next to a sampler. . . Really! They really are. I now use the B&D board more than my kit so I don't have to mic my drums. Like all synths, the sounds could be tweaked to your liking, like removing room ambiance (via shortning the times in the TVA). At least give it a chance. It was me trying this board out that stopped me from feeling intimidated to by the upcoming new Roland XV workstations.
The Bass sounds are excellent too. This is one of Roland's best boards. I was just about to pickup a DM5 or DMPro before I checked this board out. Just think about it, if you get the board instead of the module (and prices are falling for these - $199 at ZZsounds!!!), you don't have to worry about new Operating System learning curves and running out of inputs on your mixer, most importantly, everything would be contained in ONE workstation. Good luck.
The Inamous EPU.