Well the balance update is sometimes a bit meh. The fact that the mec crewman is better then all the other kits except MG3 is also pushing to many people to wander around with crewman kits just because of the gun.
The problem with the brit APC is that they so under armoured. They cant scatch tanks unlike the Russian,US,Ger APC's making them practice targets for tanks. The gun shoots to slow to light up a building, and the splash of the HE rounds is only 2/3 meter. I have had situations that it shot at me hit the wall in the same room and 0 damage..
Also the Coax on this APC and other brit armour has been put to such low speed even a G3 shoots faster.
To put it together the gun underpreforms because the lack of punch VS fire speed. And the platform it is mounted at is to big,noisy and Slow to be effective against other same class APC's