As with uniballs, they take out all comfort since there is no dampening by rubber. However, the good thing is. geometry stays as it should be, and inhances steering feeling/directness. concentric ones do that very well. Having excentric ones allows you to dail a some camber/caster, but your stuck with certain combo's of caster/camber so not really ideal. This is way easier to dail in.

bending shell? i'd prefer flexing, and yep that's what shells do, but not to worry about that. strenghtening can be done in various degrees to reduce that, but more or less, flexing stays.