As an avid user of the mentioned vehicle, i dont this its crazy to buff the dart count to like 20-25. Sure the ammo box is a life savior but just starting out with a few more would not be game breaking. TBH if they did that and moved it to 11.7 it wouldnt be bad. The tank is great on its own and can easily hold its own against MBTs and aircraft.
Its historical as the APFSDS is bigger than the HE-VT so the storage for the APFSDS is limited