Keep in mind I’ve had Marbles for about 4 months (and sometimes feel like I’ve barely scratched the surface) and Teletype for… wow, only 3 days
I won’t run through the recent evolution of sequencing in my rig, other than to say there has been one and it’s been pretty rapid and partially fueled by Marbles.
Marbles’ t2 output has been serving as my de factor master clock when I’m not using a MIDI sequence, or a slaved clock when I have (its t section does not deal well with arbitrary gate sequences). It can multiply and divide, or perturb that clock with “jitter” – in fact, crank it up and use the Deja Vu to lock it in, and it creates whole new rhythms on its own. t1 and t3 are related to t2 in either a Branches sort of way, a randomized ratchet sort of way, or a drum pattern sort of way. So it’s a neat source of clocks and triggers to drive other events, such as sequences or Euclidean patterns, which TT can do…
It also can have fun with sequenced CV inputs (which TT can provide) either for its own trigger alogorithms, or sampled for the random engine (these affect trigger randomization as well!) or to transform and mutate what it’s playing.
I guess a simpler way to put it is that Marbles is the heart and Teletype is the brain. 
I also have a Mimetic Digitalis preordered. Between Marbles, Teletype, and MD that’s my sequencing suite. It’s sort of a micro-Rene with 4 CV channels – again, something that Teletype can do. But again, I’d rather keep Teletype busy on other tasks.