Being that we've got the unbrick guide, I don't think you're in too much trouble without a backup; unless you start to tweek the performance of your phone via root, and then you don't like the way it's acting or it starts to act funny on you. If you don't use backup, there's always the failsafe of the unbrick guide, but just be ready to spend a few hours getting all your settings back the way you like them. A backup is nice because it brings your phone (settings and all) back to a state that you were once happy with before you decided to start doing experimental tweeks. It's a fairly simple process, and the scientists in this forum have done a pretty nice job with the tutorials. If you're only deleting apps that are in the OP of the "safe to remove apps" thread, then you shouldn't run into any problems. But why take any chances? IMO, taking the little bit of extra time to learn how to do the backup will save you from any possible future worries. Just be forewarned: the backup will take up about 1gb of space on your sd card. But once it's there, you could move it to your computer to free up the space on your micro sd.