I have purchased several Pro licenses through eBay to upgrade for just a few dollars each. None of them have gone bad so far. For me it was worth the small amount of money to get the group policy editor, the additional virtualization features, and some other minor advantages. The group policy editor allows one to disable and re-enable automatic updates without workarounds that might cause other issues.
“For me it was worth the small amount of money to get the group policy editor” is very useful for lots of things ... i buy only Pro versions of MS OS’es ...