Nandroid backup of .602 before SBF possible

Sorry if this is a dumb question as I never did OTA updates because I had root. Now, my friend wants me to Root his DX and I am wondering if I should make a nandroid backup of .602?

I plan to root .602.
Backup using TiB.
SBF back to Froyo.
Then Bootstrap and install cm7, liquid or miui (whichever he would like to try.)

The SBF doesn't touch the SD card right? But would restoring the .602 stock work from clockwork or is that a waste of time and I should restore his apps and phone to normal operating manner in Froyo and make the backup?