In my opinion no it is not worth taking the time to install build 7127.. My reasoning, Build 7127 is from the RTM (Release to Manufacturing) branch and so far offers no major changes to Windows 7 (a few bug fixes).. If Win 7 RC is working fine for you than I'd leave it alone and just wait for the Retail version to be released.. But of course the choice is yours..
I put it on another drive, didnt load it up with all my programs and games as Im going to run the RC for now. I did notice it was a bit snappier, but it was a bare OS. There was nothing new to look at. I cant really give you a definative answer because that is as far as I got with it. TBH if your in the postion to format and try it, cant really hurt.
I will have my new 60GB Apex SSD this week, will do some testing with 7127 on that.
First time I have had a problem with a build getting BSOD after installing Utorrent .
Have for a short while gone back to Vista while I wait for a new build .
Think there is more to my problem then just Utorrent maybe a bad burn my way not sure .