My initial thought on my build was that I would save some cash and let my DAW handle the heavy sequence lifting. It seemed a little daft to have an entire MIDI capable DAW and then replicate a portion of it inside of a Eurorack case.
I was wrong.
Hooking it up to the DAW really impacted my workflow. It seemed a better fit for augmented a piece created in a DAW with some Eurorack flavor than as part as a compositional tool. When I'm wiggling and standing there with a handful of patch cables, going to the DAW felt alien. Until the 1010 Music Toolbox comes, I've been using Ornament & Crime as a sequencer.
The point above is don't be afraid to be WRONG about your needs. Your going to order things that sound great on paper you won't use. I have a Lifeforms 8 step microsequencer that gets almost zero use. I bought a Behringer Neutron that rarely has an electron flowing through it. No matter how much planning and exploration you do. You're going to have some regrets. Take it slow, order a handful of things until you experience what direction you ultimately want to go in. You may find yourself... in a shotgun shack... with a beautiful wife... cursing set-up "A" you've spent a fortune on when in your heart you're really a set-up "B" kind of person... because you've found that's what inspires you around modular.
Sorry for the lecture. But responding helps me focus my thoughts as well as helping someone else on the ladder. I would wait on the Akemie's Castle but leave room for it in your rack. Get a feel for a smaller set-up and branch out.