In order to keep fights on the same plane all weapons should have a 60° angle limitation. Always as much as the current pitch of our ships. Especially in pvp you see more and more cruisers hovering way above or below the scene with weapons and targeting on auto giving decloaking escorts a real hard time to do something during their short live span. This has to be done with everything in the game even turrets and torpedo launchers from space stations or minefields. It's only fair to be able to return fire when being fired upon (cannon escorts).
So, for the sake of PvP, you want weapon restrictions that 1) make no sense to the franchise; 2) may lead people to give up on Beams anyway and switch to cannons; 3) affect PvE gameplay in unwanted ways.
Nah, I think it'd just be better if Escorts used their maneuverability to either get away from the Cruiser or rise to the challenge by flying up there to pound the Cruiser with their cannons.
The lower DPS is already the penalty for using beams. Dual beams with more DPS have a smaller arc and cannons even smaller. If you don't have the common sense to come up behind or in front of a cruiser instead of broadside before decloaking, that's not the fault of the cruiser pilot. Also, don't complain about cruisers going above or below, you can get up or down there as well.
Don't accuse me of being a cruiser pilot either, I hate them but only because I think a housebrick would be more manouverable. My VA is a Tac in an Escort and he's used escorts ever since hitting LC.