it's just somewhere between a capacitor and a normal battery
it has lower esr than a battery, but higher capacity than a capacitor.........
a regular deep cycle battery will last longer
a real cap will sustain short (milliseconds) voltage drops better
there's no black and white answer, you just have to decide if 'good enough' is good enough for you, for me it was, but my electrical system was already heavily reinforced, and the kinetik was just icing on the cake.
it's not even as easy as 'batcap' or 'kinetik' either, the bigger these batteries are, the higher the esr gets again..... the big kinetik batteries are basically just high-capacity deep cycles again. Rising esr with increased capacity is unavoidable with the same materials, and without a linear increase in size.