I started my update plans at 6:45pm last night, first off I did some windows updates, which promptly broke the server (oops) and as such I was faffing about till 8:30 getting it working again, then started the BES update to 4.1.7 which run without any issues, completing at 8:43 inc reboot.
by 9pm I'd finished testing to ensure things were all working.
so it only took me 15 minutes