Yes. You "cannot" restore without updating to 5.1. It just can't be done on an A5 device at this time. Sorry.
If your having bugs, I recommend you remove Mobile Substrate from Cydia> Manage> Packages.
Doing this will remove all mobile substrate addons (basically all of your tweaks). Once removed, reboot twice. Use the phone for a day. Then slowly, one at a time reinstall all of your tweaks. that should help iron out whatever glitches you had.
I wish i knew that before I started deleting a bunch of stuff. I deleted something important, now my cydia icon is gone. How do I get it back?