STO is a nice module. Lots of functionality in such a small space. If I decide I need another voice, though, I’d want to build one. In this case I am really attracted to the exos DIY module. Although appears out of stock for now.

http://www.munichen-audio.de/epages/78659294.mobile/en_GB/?ObjectPath=/Shops/78659294/Products/kit_EXOS