So, I checked and tried to update my Go 730.
I'd wiped it prior to connecting to TomTom and it offered navcore 8.351 and told me I could recieve an exclusive upgrade offer to a Go 620 or Go 6200 (both not much cheaper than Amazon) as my device was going to stop working (as expected) in a few weeks.
Via these forums I already run navcore 9.510 and the 1020 maps, thanks! Does anyone ...