Will it really be that easy to go back to my prior rooted stock state and/or back to my non-rooted stock state??
Yes...just be sure to make a nandroid backup prior to actually flashing Fission.
Sorry for the n00b question, but if I get Fission and don't like it for some reason and want to unroot and go back to stock will I only have to Restore the nandroid backup and then unroot with Z4root or is it best to go the SBF route? FYI I've only froze all the bloatware with Titanium and didn't delete anything.
BTW is Fission really that good???