I'm running ios 5.0.1 with an untethered jailbreak with redsn0w 10b2. My iphone 4 died and when I plugged it in, it was stuck on the Apple logo. Sometimes it will go the the spinning loading thing and freeze. Itunes still reads it like there's nothing wrong. I've tried booting with redsn0w and also running the 10b4 jailbreak over it.
It's not easy to say. I restore from backup often and never have trouble (except maybe once). If this loop wasn't caused by something you installed from Cydia, it should be ok to restore from backup.