Action caps hurt swarm teams, but no action caps make 2000pt gams nigh impossible to play. most figs will never activate, they'll just get beat up.

I really think the best solution is to limit the total nuber of "combat actions", that way you can still effectively use things like shield team ability and movement to get the most out of swarm teams while preventing first turn multiple KO's and the like.

The venues where I play cap actions at 5. I find it an agreeable house rule.

Action caps make large figures more powerful, which is why I'm not hugely fond of them, but they are an extremely common house rule.