Guys...
After Testing a lot of things I can come to the conclusion that newer CFWs like 4.21/4.25/4.30 have a lot of hybrid files used in order to be installed from OFW/CFW3.55
and those patched "coreos packages / .self" used (4.21/4.25/4.30) have different compatibility effects on FAT/Slim machines.
So any CFW > 3.55 will always have these risks, and should be used with caution.
I was about to release the new CFW4.25 v1.2 for FATs and the CFW4.21 v1.2 for Slims
( Yes, 2 versions, one for Slim, another for FATs, brick-proof way to go ) when I saw that team E3 have released a new CFW4.30
So I will hold back a little so i can check the new CFW4.30 coreos/patches and continue testing the new multiMAN test build by Dean in order to port it too to CFW4.30
more info will be released as soon as we get everything ready and tested well....