I suggest for the upcoming Demolution Expert 3 a new remote for C4.
Instead of being radiocontrolled, it should be triggered by a well-placed shot.
This way, Demolution Experts wouldn't be able to trigger them with their low gun skill, but teamwork instead with snipers.
So, the Demolution Expert will just be able to place the hidden explosive, while a sniper could spot and trigger it to make some damage to a group of armed foes.