For 2 battery TC I have Smoant Battlestar (not sure if you can still find that one), Smoant Cylon and just won Innokin Proton. But all I can say is they work, I haven't dropped them to death yet to know if they're actually sturdy, only make predictions.
I think only the Battlestar has been dropped and that's been light falls on carpet.
I'm curious about the Proton, it doesn't feel sturdy like a SS case but it's a lot lighter so may not crash as bad. I guess I have some case wear and it looks like it is some kind of metal for at least parts of it.
Cylon feels sturdy but has the weight problem that goes along with that.
Battlestar is a magnet cover similar to Wismec so that might go flying in a hard fall but the case seems sturdy.
Cylon and Proton may have a battery door failure with a bad fall at the wrong angle .
My Joytech Cuboid took a lot of hard drops over the years before it stopped reading right enough (it never did agree with other mods which is why I didn't replace it with the same).
Single battery, my Joytech VTC mini assortment has had a few falls (but nothing like my Cuboid went through) and all 3 live.
Bad thing if they've been time tested they're probably not a new model.
My RX200 never gets carried to be dropped.