If you change one (def or attack) I guess it will be logical the other one is changed also, but i dont really think cath attack fleets are that bad.. so killing a small percentage of the emped ships might make it a little bit too good even. On the other hand, there's NO REWARD AT ALL when you selfcover as a cath vs your own incs.. obviously, they'll land it anyway as the worst thing that can happen is they get stunned. You used to get 100 xp for defending your own planet vs landing waves.. but they even removed that little reward. Killing 5-10% of the emped ships would prolly still make most of them land vs emp only def, but then you get at least something in return, so the suggestion gets my vote tbh
Will be a lot less frustrating for most cathaar planets. Another thing you have to take into account is the fact that those waves covered by emp ships only, drain a lot more and especially longer ally/gal deffleets. So YES give us cathaar players something in return plz :d