That matters. Do you want to have access to the PSN? 5.00 M33 CFW's are no longer able to access the PSN. That includes the Store, Remote Play w/ PS3, and most of all online games.
5.50 GEN-A/B may not be as homebrew and app friendly, but most stuff works on it and it has more up to date FW. For GEN, the PSN works like it does on OFW PSP's, so you are not blocked from it like you are with 5.00 M33-6.