i went from 3.55 kmeaw to rebug 3.55.5 otheros++
for compatibility reasons i see no difference, all games who are working on kmeaw are working on rebug, too.
only one time at the install of a .psn release i got a throphy install error what was simply solved by mount some random game over multiman.
could be there are some game incompatibilities but i for my self never got them.
CECHA00 (europeanized) 750GB REBUG 4.30.2 REX, PS3 Switch/Swap Mod - YouTube
CECHA12 (europeanized) 160GB REBUG 4.21 REX, (bricked/needs new Flash), CECH2500B 60GB REBUG 4.30.2 REX