I'd say it's worth it. I'm not saying customs are a poor binding by any means but the Cartels are just much better. You get much more comfortable ankle/toe straps, auto can't footbeds, stiffer highjacks etc. I think the stiffer setup would suit an all mountain board like the mountain twin better than that which the customs can provide.
I use the Cartels and Genesis' and they're both great. Can't really fault either of them.
So, TTs are shit and Rome 390 build quality > Cartel build quality? LOL! Where in the hell are you finding these reviews? A lot of people really like Rome bindings, but there's probably been more threads on here about quality issues on Rome bindings than all other binding manufacturers combined.