That's a good use of the incapacitation system, I'm all for things like that. On the merits of any fight itself, it's almost impossible to make a fight, at its core, not subject to class stacking. If it's weak against one damage type but not another, you have class stacking. If it's better to be at a range or close up, you get class stacking. If you need more AoE or single-target, you get class stacking.

Something that requires the unique skills each class brings is the only thing that can really alleviate it and that's where Incapacitation shines. Though honestly I'm not a fan of how the zone hit (Front, Side, Back, etc...) detection works sometimes. I'm not sure how possible it would be for them but if they could allow us to target the different parts, that would be great. They could keep the same restrictions we have now or go further and allow all attacks to damage them but only the specific incap attacks can break them or they do a significant amount of damage.

Battle Regimens could also help dissuade class stacking if there were unique effects that only certain classes could add to the regimen.