Just some experiences to share:
Was on stock rooted EL29 GB. Flashed to Agat's latest themed FC22 with only doing a cache and dalvik wipe. Actually worked pretty well after I did some cleanup. However, there were a few glitches so I wanted to go back to my nand of EL29. I was too lazy to Odin back to a EL26/29 rom so I just took the plunge and restored my EL29 nandroid using this recovery. There was no problem.
Long story short is I belive that flashing back and forth between GB and ICS rooms is fine as long as both are TW based. Once you throw anything AOSP in there things have a potential for brickage. Mind you, this is only my experience.
PPL don't follow proper steps it Cleary said on op that to flash this ROM up have to go back to proper clockwork mod or flash cm7 or miui which has the right clockwork mod to flash Cm9 or other aosp rom.
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