Getting close to shipping so will let you know. As far as the setup, it does have some options meant to be changed via C64.
http://csdb.dk/release/?id=149816
For use in a MBsid, would either have to pre-configure it on C64 (would be a bit of a pain) or add extensions to the PIC firmware. Would like to be able to choose SID type and channel muting at runtime. Not sure the default config, so have to work that out when I get them in hand :)
Yogi