I have the GM of Lion that came out a few weeks ago. I went a head and bought it just so my account shows I have a legit copy and I just like paying for good software 🙂 So my question is should I even bother running that installation? Will it even let me?
If you truly have the GM build, then, no, don't bother.
To make sure you have the GM build and not an earlier beta, go to Apple Menu -> About this Mac and Click Version 10.7. If the build number displayed is 11A511, you have the GM build.