You could make the most of modulation sources with a DPW Design AV-1, your two inputs can be attenuverted, there is also a SUM output and a A>B output so lots of options for screwing around with your CV signals to create more. You can even throw a couple of gate sources at it and get a new sequence based on the two input.
That HN 3xMIA does look tempting though ;-)
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.