I'll second that! That's a killer MIDI interface for the price, and it brings up a good point: don't always try and put all of the modular's devices IN the rack...sometimes outboard is the right way to go. Like here, apparently!
Other than that, this looks good...but again, I don't think you're going to need a buffered mult. A regular one would be fine, since you're not likely to need to branch one CV out to, say, seven or eight sources and keep them all on-scale. Also, having the other two percussion voices of the 'holy trinity' of kick/hat/snare might be a good swap-out for the Yarns if you go with the outboard MIDI, and you'd still have a bit more space to play with besides if you use small-hp snare and hat modules.