The VS.NET installer has gotten a lot less terrible since the 2005/2008 days, although it used to be pretty dicey. One may now upgrade with little to no fear of a nightmarishly borked install state... that said, it's wise to use VMs exclusively for development, so rolling back to a pre-update snapshot is an option.

I heard many complaints about SP1 slow starting and getting stuck in 'Shutting Down'. On top of that SP1 has zero new features. Bunch of so called security updates. From my perpective i'm using the stable version.

If thing go awry i would need to waste a day or two reinstalling the OS again. It's very easy to resist installing this update.