ARE BLU E CIGS COMPATIBLE WITH ANY OTHER E CIG CARTRIDGE?
No, the cartridge are not compatible.
Empirical evidence suggests otherwise - I have, just minutes ago, very successful used a SafeCig Mini cartridge with a Blu battery, and vice-versa. I'm going to test charging with the Blu case next.
My Blu starter kit came with defective parts, and customer service was abominable, so I was getting ready to ship back. If this works, I may eat the cost of the Blu starter kit, just because SafeCig doesn't have a rigid case option.
SafeCig Mini is vastly superior to Blu, at least for MY personal tastes - obviously, different people enjoy different things. Smoking a Blu is like smoking a hookah - same light throat hit, same kinds of flavor. SafeCig feels like smoking a cigarette - palpable throat hit, flavors much more like tobacco. They just need to add more accessories for the Minis.
TL:DR - SafeCig Mini batteries/cartomizers and Blu batteries/cartomizers appear to be compatible.