I was on 5.0.1 and went to 5.1.1. The only difference I noticed between the two is the ability to edit Photostream pics right from the phone, which is kind of a nice touch. I personally like keeping my firmware relatively new and up-to-date to avoid any conflict issues. Some iTunes apps work only with 5.1.1 and not with 5.0.1, and you can't tell if they do until you load them and they crash your phone. Sure, it's a simple matter to just delete the app in question, but it just makes things a lot smoother when you don't have to worry about those conflicts. Plus, it isn't like it's a major pain to make the whole switch and re-jailbreak, in my opinion. Especially if you've backed up stock apps and used APTbackup to back up Cydia apps. It's practically all automatic.