I've read in the past about difficulty using the pigtail USB and having to connect to the USB ports on the back of SV directly - not a good deal since you'd have to remove the instrument cover panel for each Firmware or Nav database update (or install your own pigtail from the back of Skyview.)
FWIW, I've never had that problem (knock wood), including the latest 5.1 Firmware update. I've done 5 Firmware updates and multiple Nav Data and Obstruction data updates using the built in Stein wiring harness USB port.
Not liking Van's USB port location underneath the panel, I skipped that place, and installed mine on the LH front panel where it's much more convenient. Besides the Firmware updates, and the Nav and Obstruction updates, you'll want easy access to that port for loading Flight Plans you can create at home, and also - now - for Data dumps, using the new 5.1 Data Acquisition and Storage capability.
Bob Bogash
N737G
MLG SB almost done