I agree with ronin in that generating patterns in the modular would be much more interesting than with a digitakt
but that leads you to the problem of case size - forget the intellijel 4u and go directly to 6u or 9u - you will use it
I also think it's interesting to at least consider having some basic building blocks to roll your own drums if you are going to go this way - noise sources, filters, vcos, vcas, snappy envelopes - rather than just buying all pre-built modules that lots of other people have
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities