The SO carries APX 7000 portable radios already, which are dual-band capable. Is RF Band 2 not 700MHz, or are they awaiting enablement from their preferred service provider? They currently have UHF GPS antennas on their radios, which leaned toward the confirmation of them being on UHF still. However, outside of Sheriff Dispatch, they also operate on the county regions, including Police Region 4 and 7, which are 700 only. No patching magic behind the scenes.
Unless they are unprepared for migration to 700 using their existing portables, the only physical drawbacks hindering the move are 1.) The single-band portable antennas and 2.) Mobile radios in one or more cars being single band 500 only, perhaps some XTLs in play. Another thing to consider as well is that almost 80-90% of their radios do not follow the county-municipal code format, which SCC might want them to rectify prior to going 700.