Yes, the reason P3Droid states the other way is because he has so many different phones and the method he posted works on most or all of them.
The only addition I would make to the overview of SBF files posted above is that none of the SBF files will write to the data or cache partition by default and so to truly return to a "factory state" requires a factory reset/wipe of those partitions.
This is best done before a flash if you anticipate having any problems ie; you are on the OTA 2.4.33 already and are flashing the 2.4.29 SBF for any reason.
If you are using the bootstrap recovery and you want to keep your data partition for the sake of ease, then you can select to wipe cache by itself.
Then, press/hold the up arrow on the keyboard while pressing the camera key to reboot from recovery. You will go directly to bootloader then and can connect the phone to PC and proceed to flash.
The reason this trick is important and useful is because if you were to reboot normally from the bootstrap recovery after wiping the cache partition it would be rebuilt again with the 2.4.33 components that you just wiped. Holding the up arrow and going directly to bootloader avoids this problem.
This is only if you are intent on preserving data for some reason.
You can also do this after you have flashed but it will bootloop and have to get into recovery and it's generally messier and scarier if you do it that way.
First of all thanks for a quick and detailed reply. Thanks to Tebower too.
Let me see if I got all this right. The custom recovery bootstrap tool is a program that allows one to backup and flash a new rom onto the phone. It lets you run a custom rom, say the Fission 2.4, that didn't come from Motorola.
If things go horribly wrong while you are flashing a new rom, and you can't boot into the system, then you use the sbf file. You need to use developer tools on a Windows machine to flash this file onto the phone and return it to its factory state.
Do I have it right so far?