A SBF file is basically the original image file of the OS the manufacturer uses to install the OS onto the phone with. This process is pretty much what Verizon/Motorola would do to repair a phone that appears to be bricked or to be suffering from unfixable issues.
I went back to stock, then upgraded OTA back to the latest Froyo (3.8.7). I didn't have any software problems with Gingerbread except I didn't like the GUI. So much happier now with Froyo.
Interestingly, I orginally upgarded to GB OTA. Now after I've reset my phone, the GB OTA update isn't available for me. Not that I want it anyway.