Neil,
I hate to say it but I think the answer is none that you can see. However, rather like a car, the forum is now up to date with the service schedule.
The look and feel of the forum is customised for the LMC so a standard upgrade won't affect that ie: banners and layouts.
But, there are add-ons and other bits we can do with the Forum and you usually need to be on the latest version to use them. So we're looking at those and that was the main reason for doing it.
There is also the 'if it ain't broke don't fix it' view
and the fact that it is such a well used forum I don't want to take it away from people too often : especially once we hit summer and we're out and about. There are 400+ users all around the world and you can be sure that pretty much any time of the day of night someone will be having a look !
There you go ... hopefully answered
Steve