I think to make the Black Hat a more viable choice against the EMP Grenade they should allow you to pick up any equipment that you hack.
For example, you hack a Shock Charge, you can pick it up and redeploy it at your leisure should you feel so inclined.
However it would still only destroy streaks as it now normally does.
I think that this would perhaps balance it better against an EMP Grenade as a competitive choice.
If you are worried that this out balances it against the EMP Grenade, you can limit it to one spot, such as you cannot currently have more than one Smoke Grenade. I, however, don't think that adding the ability to pick up hacked equipment would make it more favorable to the EMP Grenade, just a more competitive choice.
Just to be clear, you cannot hack a grenade that someone threw, but you could hack a C4 that someone left just lying there.
And if you are fast enough on the trigger, you could hack a freshly tossed C4, but that would take a lot of quick reflexes so I don't think that would be a big issue.
I run black hat on one of my FAL classes because I needed a tactical that I knew I couldn't use in any way against enemy players. Gotta focus on gunskill...not emptying my pockets at people, then using my gun as backup.
Black hat is fun to use against people who use BB/shock charge, and good for eliminating the occasional UAV/CUAV