From what I understand, sbf'ing is where you connect your phone tho a computer while the device is in bootloader mode, and push a .sbf file to it with an sdk program such as RSD Lite. Usually, the .sbf is the custom recovery program, which is essential to the whole rooting and romming process.
In answer to your question, yes. If you create a nandroid backup of your phone prior to doing anything but sbf'ing, then when you restore that backup, your phone will once again be like you've not done anything to it. If/when you make the backup, I personally recommend selecting all the options because it saves from having to download any of your apps, but also i'm still learning, myself, and don't know which parts of the backup are vital, and which are conveniences.