any downsides to "restore from backup"

subscribing to thread...I'm interested in this as well.

 

Don't think so. I don't think it copies like... the whole OLD firmware, just the important parts. Like which apps you had synced, where they were, what the save data on those apps is, etc. Nothing laggy at all

 

I had an issue with a 3G that was extremely laggy with very poor battery life (I got about 4 hours battery with the phone locked in my pocket). I reset the phone and restored from backup but the issue persisted. I finally reset the phone and set it up as a new phone and the issue disappeared.

So, something was corrupted and crashing/running at 100% CPU that transferred from a backup. If you are having issues with your old phone, don't restore from backup. If not, you should be fine.

 

any comment to this if the old phone was jailbroken? I wouldn't think it would make a difference...or am I wrong?