Like I mentioned, it's all a matter of taste, but I find (and I think some folks here would agree) that the cost to effectiveness ratio of modular drums is not all that great. I've spent a fair amount of money on drum modules and rhythm sequencing options and ultimately enjoy the process and results of my $300 Behringer RD8 much more than most of the drums I come up with in my rack. Basimilus's sound and modulation versatility are excellent, and it's fun to stumble upon interesting or random rhythmic ideas with modules like Euclidean Circles (which I may end up buying one of these days), but overall I find modular drums as a good supplement to external drums. Elektron makes great drum machines, though I didn't click with their interface, so the immediacy, versatility, and value of the Roland x0x-style drum machines makes a LOT more sense to me. Drums and polyphony are where I find weaknesses in the modular approach, so those are the external sources I incorporate with my rack.
Edit Check out the WMD drum modules. The Crucible, Crater, Chimera, and Fracture are pretty awesome.
The Cs-L looks killer. I've got the Furthrrr Generator and you'd have to pry it from my cold dead hands. :)
After you start getting some modules in your rack, you will know what you need next. You will find yourself reaching for something that isn't there, and that's the next module you need to get. The Expert Sleepers Disting Mk4 or Disting EX is a good module to get early on because it covers so many of those functions that you don't realize you will need. Take a look through the manual for the huge list of functions it can serve. It's kind of menu-divey and not super fun to use, but I'm finding it more and more valuable every day. I'm still finding new things it can do.
Keep us updated and let us know what you decide. Have fun!