I have Rockbox on one of my v1 players. The 3.1 release adds a couple nice features to the already existing platform (like back-light fade-in & fade-out), but no major changes over 3.0.
You cannot view it as a replacement to the Sansa firmware though, as it is not. It is an ‘alternative’ and a ‘dual-boot’ system meaning it resides next to the OF and the player can be booted in either firmware at will. You still need the OF for certain functions so it cannot be eliminated.
Some like RB. Others don’t. True, it adds a multitude of features and functions left out of the original Sansa design, but it is not the ‘be all, end all’ firmware solution and can be tricky to install and navigate for some with the sheer volume of settings and adjustments one can make with it. The way you speak, I doubt that you would have any troubles along those lines though.
Some people have had problems with the v1 firmware update 01.02.24 and have actually reverted back to the previous version 01.02.18, a more stable release. Personaly, I never updated to it in the 1st place. I had no problems with the .18 version (still don’t) and have always adopted a ‘wait-and-see’ attitude when it comes to any soft or firmware updates. ‘If it ain’t broke, don’t fix it’ is a credo I have respect for.
Here are a number of discussions on the subject. Good Luck with your decisions. 
