ok,im a little confused... but if im understanding you correctly,you rooted and downgraded to froyo,then you restored a backup in recovery of your gingerbread rom. if this is correct, then you should be still running the froyo baseband.
all you need to do is download unrevokeds "forever" tool and flash it in recovery. its linked in the first post.
after you do this,boot to hboot to verify that it is indeed s-off.
then flash the gingerbread or froyo RUU,wichever you might want to be running. once youre s-off,no need to downgrade back to froyo in orger to run the GB RUU.
i hope that answered your questions.