Here's my problem. You want to restrict the riot shield, when everyone who has ever used or gone against it, knows it is crap offensively and defensively. Try to limit the nerfing to the C4, Danger Close, or Extra Lethal. The setup that abuses the C4 requires a heavy point investment. The riot shield is just a way for people to get to extreme close range and ensure C4s effectiveness. Even without the shield, the C4 is powerful on its own - you can abuse the same tactic just by popping in and out of cover and chucking the C4.
Several ideas I agree with on C4:
* Drop the quick detonate (Double Tap reload)
* Make it have to plant itself first before detonation
* Shorten the throwing range
* Lower the blast radius.
Don't force an obvious restriction on me like "can't use equipment with the riot shield." Also, until the Riot Shield becomes a competent weapon on its own, do not even consider nerfing it. I am tired of being forced to swallow all this crap that it is for support; that's no excuse for sucking offensively while sucking defensively as well. One of the best things I learned while playing Mass Effect 3 MP, is that just because you are designed for support doesn't mean you get to suck offensively as well - you need to be able to hold your own when isolated. The riot shield and its respective set up has to punish people at close range and it cannot do that unless the player has C4, uncanny skill with a throwing knife, or can quick swap to dual pistols.
Now if was able hipfire my pistol while the shield was out, not get bullet cracks, or make my melee a OHK, then maybe you might have a case.