No shouting while grappled
This could lead to some interesting situations where grappling makes it easier to acquire people stealthily. Some may think it is overpowered, but SIC still exists, it's not a total death sentence.
Can't break out, but can avoid suffocation
As far as I'm aware, this is not a mechanic, but feel free to tell me I am wrong. You either get choked or you break out. There should be a middleground where your character has just enough skill / strength / finesse to avoid suffocation in the grapple but still can't break out. This is realistic, there are many real-life techniques to avoid suffocation from choke holds.
Thoughts? I think these would balance out nicely and encourage more roleplay-focused grappling, using it to reposition or kidnap enemies rather than only be used as a primary offensive maneuver.