Have you thought about bringing effects pedals into the mix? If you play guitar or have external instruments, Adventure Audio Merge could be one module for consideration, and would also give you input/output for pedals, as well as an envelope follower. Another option to think about to just bring in pedals for audio processing would be Malekko SND/RTN. I find bringing pedals into the signal flow a fun way to expand the palette.
As for filters, perhaps something really aggressive like Flight of Harmony Plague Bearing or Imp? ALM Busy Circuits MUM M8 could also be considered if you would like to have that classic Akai S950 Low Pass Filter.
REX50 isn't a bad choice, actually. While it's not anywhere near being a state of the art reverb processor these days, as a "module" that's accessed through something like a SND/RTN it seems like a good fit within a modular patch. You get that lower bit-rate "dirt" with older FX units like this, and that's a really good additional character to add to a sound when you can tamper with it further.
Have you tried out any of the settings on your Disting? There are plenty of effects modules out there. You can try out various effects and figure out which ones work best in your workflow. You seem a bit limited on space. I've had some success with TipTop's Z-DSP. I'm also considering a Chronoblob Mk2.