Honestly, I'm waiting a few more years for the new sodium-ion battery tech to come into the mainstream. It's got all the benefits of lithium with none of the fire hazard, at only a slight weight penalty. It's already on the market so won't take long for victron etc to catch up.
In the meantime, I'll stick with my AGM lead acid. Saving 20-30kg isn't going to make much difference for me (and the weight is low down anyway).
OK, that wasn't helpful.... stainless is fine for a battery box assuming there's no chafing or shorting, but where is all the heat and gas going to go if it