I thought about it, but decided against it. I even read through the Rockbox manual. What I didn't like about Rockbox was that using it voids the player warranty, some people have bricked their player using Rockbox(although this is probably rare), and installing Rockbox may permanently disable the player's ability to play protected files(I have some Slotradio cards).
Rockbox seems much more complex than the Sandisk firmware, however it does offer many more settings. I rely on the resume feature on the the Clip+ for Podcasts(Rockbox doesn't have that).
I guess a good analogy may be comparing Rockbox to a manual transmission car, and the original firmware to an automatic transmission car. Which is better? It depends what you want.