First off, the time you are EMPed should be on par with the other tactical nades.
Secondly it shouldn't be able to destroy the AGR, Sentry, and Guardian, only stun them so you can either run by them, or get behind them and destroy them with your weapons. If I work hard for my scorestreaks you shouldn't be able to destroy them so easily with some you can just equip on your class and whip out in 1 second.
Lastly, the range is huge and it doesn't respect walls. If the range is going to be that huge it can't be allowed to go through walls.