BRCA Homologation lists are only needed at events that decide to use them, so nationals, and
some regionals ([I]
though not all, we don't use them in the SW currently for example, as our scrutineering only does the size/weight checks).
***EDIT*** I've just been informed by BRCA offroad section officials that use of the homologation lists at regional events is compulsory, and not part of the regional variation sections of the rule book. My apologies for the error. I consider myself duly corrected!
Although I believe the homologation process does do some safety type checks, it's main purpose at those events is to insure a level playing field for competitors, so it has no bearing on insurance. As I understand it, the BRCA insurance is only there to protect you from others suing you, and does not provide you personal accident cover.
Clubs don't normally bother using the BRCA lists for their regular racing, so any lipo is fine...however it's good practice to stick to hardcased ones at the very least...purely for the extra protection from puncturing.
It's my understanding that the only important part of the BRCA membership and insurance that relates to lipo's is in the general rules that state you should charge your drive cells in a fire proof container.