Fun and Games with WIndows 8 dual boot

A word on setting up the dual boot on an existing machine by the way......
Obviously I already had a Windows 7 instance on my work laptop as that is the company SOE, and that has a lot of 'customisations' on it, so I didn't want to have to rebuild it.  No problem I'll dual boot Win8.
HA - that's all I'll say to that,
HA.
There I did it again.
So what were the problems?
I could not - no matter what I did - get Windows 8 to start on a partition that wasn't Disk0 Partition1
(give or take the system reserved partition)
So that necessitated moving the Windows 7 partition to a second Primary partition. This in turn means that the drive letter changes, and you cant change it because its on the running OS.
OK we'll come back to that.
Lets get Windows 8 on the first primary partition.  It still didn't want to know, hmm maybe this is a dud download - it extracted OK, but maybe.....
Tried it on a virtual machine (VMware Workstation 8) works fine - nothing wrong with the install, but hang on, the system reserved partition is 350Mb now.  That was always an option on 7 but I only ever used it once for a professional setup.
Tried to install it after removing the existing 100MB and hey bingo - success.
So now it works but Windows 7 is dead as all the stuff it expects on C: is now on D:
Do a quick regedit to change the dosdevice=d:\ to dosdevice=c:\ and we are good to go.
Does Win8 need that 350GB system partition?
Is this going to make in-place upgrades for the likes of SCCM and Altiris more than a little difficult?