Something nobody ever said about the IOS hack, is whether the hack is independant to the IOS version or not.
is the hack based on a protection which will grant access to all the IOSes, or is the hack focused on a single IOS slot? (wiiu has different slots too, right?)
for example, if the hack is based on "IOS36" and that IOS slot has not been updated since 5.3.0, then you can update or stay where you are, and the hack will work on all versions from 5.3.0 to 5.5.1.
on the contrary, if the hack is not slot specific but more general memory targeted (like MEM2 PROT on wii) and only 5.5.1 can patch it, or if it's specific and the IOS used by the main menu has been updated since your current version, then updates will probably be recommended.
without technical information, it's hard to suggest what to do.