Hi, Michael31986,
Yes, setting your device up as a new phone can solve many problems, and no, the problem with backups that have been reported here are not in our heads. The results are quite clear. Many folks have reported that their backup files have been reported directly by iTunes as being corrupt. The reason is that bugs in the V2.0 iPhone have occasionally corrupted the data on the phone, and once that data is backed up, the errors are copied into your backup file. For folks who then perform an update procedure instead of a clean restore, those errors can be copied right back onto the device. This can lead to a wide variety of different problems, including the infamous "Apple Logo of Death", application update errors being reported, application hangs or crashes, etc. No B.S., I've experienced all of these personally, and repeatedly (we run 90-100 applications on our four iPhones here).
When you've got a corrupted backup file, iTunes itself will often tell you (as many folks have reported here). When that happens, restoring from backup isn't possible at all. Unfortunately, iTunes can't detect all of the kinds of corruption that may be present. When that happens, iTunes will merrily copy the crap thats in your backup file back onto the phone, and you'll start seeing weird bugs that can drive you nuts. Fortunately, sync is a far better means of dealing with corrupted data, so that you can nearly always sync content back onto your device even once the backup file is corrupted (to make a long story short, the sync process helps to keep the global files intact, even if individual data items are somehow corrupted).
As long as you've been syncing your phone with iTunes before you want to upgrade to a new release (and you've synced the right things such as your contacts, mail, etc), your PC/Mac will contain most of what you'll need if you choose to start clean with a device restore - even a DFU restore, which is a pretty-much guaranteed way of getting you out of any software problem than can occur.
So the question is, what do you lose by following a DFU restore, setting up your phone as a new device, and then syncing? For one, just about any data corruption which may have occurred on your iPhone! Practically, you'll have to re-enter your basic iPhone settings, and your application settings. You'll lose the 3rd-party application data like game high scores or logins, and you'll lose your SMS messages. You won't lose your email configurations, your contacts, your photos, your music and videos, or your 3rd-party applications. Again, you do need to ensure that you sync your device before performing a DFU restore, but that's not exactly a painful procedure (on version 2.0, you can skip the painfully slow backup, and on V2.1, the backup's very fast).
What really surprises me are the literally thousands of posts here made by folks who invest huge amounts of time chasing these kinds of bugs, when the solution is so simple! It takes me about 15 minutes of work to perform a DFU restore and to reconfigure my device settings the way I like them. Sure, that's with some practice, but it's typically less effort than many folks put in here just to post about their problems! Once that reconfiguration is complete, you just sync and everything else will be copied onto your iPhone.
If your iPhone is crashing, hanging, generating errors on application updates, or especially if you're seeing the "Apple Logo of Death", performing a DFU restore, setting up your phone as a new device, and then syncing content back to your phone will do more to get you back to a stable phone than anything else you can do. Just be prepared by regularly syncing your phone, so that the data that counts is ready for you!
Cheers!
Mark