Right on about the 48 mic inputs. The card to have at FOH, though, is the io16 option card.
http://www.avid.com/us/products/venue-io16-option-card The 8 TRS and 8 AES inputs and outputs are available in addition to the fixed 48x32 architecture of the SC48. Adding more conventional XLR i/o will not give an increased i/o count, those are limited by the architecture.
Scovi covers this in the Version 3/SC48 Remote webinar that was recently added to archive. Well worth a watching. :)
http://apps.avid.com/events/webinars...ex-archive.asp