I've run them as Limited User Account's and all the faff of AV, AS, Autostart protection, Group Policy program restrictions etc all running and slowing their browsing/downloading down, and still managing to make a mess when I come to use it.
This combined with a Ramdisk for the sandbox works flawlessly so far (Only a day

I'm still running AV/AS/Peerguardian/Spybot resident/MS Defender and group policy restrictions for the time being, but, when I'm confident enough I dont need AV/AS bloatware running and just sandbox everything well, you've got my money.
Excellent stuff.