Hi, Im new to macs and OS X so can anyone please tell me, whether the El capitan GM will wipe out my mac if Im running El Capitan beta? Or is it safe like any other beta udate?
Whilst there's always a hypothetical risk, the installer should simply overlay the GM on top - you'll keep all your settings, documents, and other data, with only the OS being updated, just as with any other update.
The installer does recommend having a fresh Time Machine backup available. Just kick one off manually and let that complete, then proceed with the update, so if anything should go awry, you can recover from it easily.