I don't know if it's a matter of too many voices per say, as much as it is a matter of too many hp taken up with voices. Here are a couple things to consider:
-- Do you need the Nerdseq expanders? This is still a fairly small system, and I find it a little unlikely that you'll need so many extra triggers and CV outs. Maybe start out with just the basic sequencer, then add an expander later once you're sure you need it (and you may find that you need one or the other, but not both).
-- I'd go with BIA over Taiko just for hp savings.
-- 10 VCAs seems like a lot for a system of this size, so I think you could cut the DVCA (yeah, yeah, I know, you can never have too many, sure).
-- The Castle is huge. If you're dead set on it, you might swap the Megaslope for a function generator that uses fewer hp.