Updated firmware seems to be behaving well, none of the previously reported issues . dropouts etc.. Hotspot connection and Bluetooth links both worked faultlessly, codes only had to be input on initial setup (Mobile = Sony Xperia Z2).
Only thing I've noticed so far (this weekend) was system twice - on both outbound & return journeys - went to "navigation system loading", but when it loaded seconds later it returned to the current route and resumed from where it left off, so no real problem.
A little niggle, just had to hide the menu bar after system resumed!