I love this idea, mostly because it takes 3-4 Pounds from Jiggs to break a shield, and after the 2nd Pound, most people know better then to shield the 3rd hit and either go on the defensive or offensive.
I think if Pound broke in 2 hits (as in immediate consecutive hits), or 3 hits if they got away and let it recharge for a bit, it would worth hitting shields with, considering how easily punished it is if you hit someone's shield with it.
Thinking about it, shields shouldn't regenerate AT ALL until you do damage, and the amount of shield recharged should be equivalent to the amount of damage done.
I'd like to see more moves like Bowser's Klaw that allows people to grab from the air. I think it would be cool to see "status effect" moves likes Jigg's sing and Mewtwo's disable, only USEFUL. Maybe a move that disables aerial moves, reverses controls, slows character, weakens character, steals health, etc.