My instinct would be to remove the drum parts, actually, and not the BitBox. You can use the BitBox to store textural loops very easily, which fits nicely with the soundscape aspect. But with the way drum machines are going at present, it might be a better move to go with a NON-modular solution.
This'll probably cause a big shock for some users, but I'm going to actually suggest getting some...yep...Behringer stuff. Namely, an RD-8. Yep, Uli actually managed to get this fairly right. Each track has an individual output for discrete processing of drum sounds, there are three trig-out tracks, and the sequencer works pretty much as one would expect for an 808, with some added conveniences. Now, in addition to this, I would ALSO suggest adding a Doepfer A-119 to the modular, as this is an external input preamp that also has an envelope follower and level comparator, meaning that you can feed individual outputs or even the entire machine through the modular to screw with them there. It also has a decent onboard filter on its own.
Then to that, I'd suggest adding Elektron's new Model: Cycles, which is an FM-based "groovebox". Ignore that stupid term, though...what it would be here is a source for metallics, percussive weirdness, etc. And yes, BOTH of these are easily locked to the modular's clock; the Elektron will want to see a MIDI clock which will require the PEXP-2 expander for the Pam's, but the RD-8 can take an analog sync directly, meaning you can mess with the RD-8's clocking via a direct connection to a Pam's channel. And by putting all of this under a DAW clock, everything locks up nicely, even if you're (ab)using the Pam's to mangle the timing.
Then, to put the cherry on the cake here, get some cheap (Rowin, Donner, Caline, Cuvave, Azor, Mugig, et al) effects pedals. Sprinkle liberally amongst the individual RD-8 outputs...fuzzes, overdrives, bitcrushers, delays, etc.
This is actually a better solution for drums, from my experience. What I use is definitely not identical to this, but there's very much aspects of this in my own studio that allow me to get really busy with percussives. But the fact is that electronic percussion is actually STILL something of a "weak link" in modular synths. Either you don't get enough functionality out of rather spendy modules, or they just don't sound all that hot in the first place. However, one manufacturer there stands out for creating a bunch of totally wrongheaded modules that are EXCELLENT for bangers 'n' clangers, and that would be Moffenzeef. And yep, you can fire those off of the RD-8's trigger channels. But again, I'd suggest putting these in something like a Palette skiff...keep your functions separate. This not only frees space in the main cab for synth-centric modules, but it gives you space for a bit of logic to mess with timings, as well as a small mixer and something "evil" for drum-specific processing, such as a Schlappi Interstellar Radio which is designed to make everything sound utterly, totally trashed, very early Aphex-ish.
And while it might sound like having all of these separate devices would get confusing, the opposite is usually the case...since you know that "X" noises are coming from this box, "Y" out of this other one, and so on. No need to chase down your mingled patchcord signal paths in a single cab. Having done live techno sets this way back in the 1990s, with NO laptop, NO software, and NO MIDI save for a TR-909 sequencer signal to a CZ-101 (yep...all CV/gate and onboard sequencers!), I can assure you that this methodology DOES WORK...and it's a lot more streamlined than you'd suspect!
