Migrated this morning to Vivaciti, could have been smoother, but Enta CS sent me a username that included an extra vivaciti (vivaciti.vivaciti.com).
Still, Vivaciti's support was excellent. Multiple reboots whilst trying to sort the problem out (including the few times I tried an older router) had forced my SNR up, but my superb TP-Link router soon settled back down to a 3dB downstream SNR. Currently synced at 13183.
Thanks to Karl at Vivaciti. No thanks due to UKFSN.