Henkaku offers a lot of customization and control over the Vita's internals, PS Vita game "backups," excellent support for a large number of retroarch cores (SNES plays pretty much perfectly), mod support for some games and more to come in the future. Can run HBL as well for a lot of psp homebrew. PSP and PS1 games are not supported yet though.
3.52 is EPSP exploit which allows PSP backups and homebrew.
It comes down to the question: are psp backups really important to you? If so, stay on 3.52. Henkaku is waaay better. though.
Thanks, this info really makes the decision a lot easier.
I only got my vita yesturday morning, so I was very much unsure what is around the scene, except I knew I was on a version that was seen important at some point.