It appears we may not be stuck on 3.55 CFW much longer. Deank has provided us with some conformation that this new CFW labeled Red Power's 4.21 is indeed real. multiMAN has been updated to version 04.06.00 so this CFW is compatible when it is released to the public, There also was speculation that this CFW may need a reDRM dongle in order to use the CFW. That was false information as deank also confirms this CFW will not need a dongle of any sort.
Source
So this seems very promising. It continues on to say that the MultiMAN update hasn't been fully tested with the CFW yet, but since it hasn't been released to the public yet that makes sense.
I'll be keeping a close eye on this one.