You got software compatibility issues, if you need to restore alot.
I would suggest you look at dual booting your iphone and keeping a stable version on hand on one partition and using the sim software taht allows you to save contats read contacts off sim ( forget name thinking isim ) that way when one one partition down you are always back up and have all your contacts at hand, or you could just double sync contacts to each partition
http://wikee.iphwn.org/s5l8900:dualboot
.OPps. my mistake, you need to have a script to change partitions so if can't boot into one you can't switch. But never the less a great idea to help test compatibility