Seat firmware 0996 or 1020 is latest. Don't try anything newer as it'll turn it into a less than useful brick until you use the SWL recovery CD. v7 maps work fine, not upgraded ours past that.
If you want more sell that one and get a VW RNS510 off eBay and enjoy the latest features + SD card slot. Seat units still seem to sell for decent money for a reason I can't quite understand lol.