@Iron_Guard8I agree that the ability shouldn't increase his rate of fire. I understand a lot of your arguments and believe that they reflect you experiences made in the game accurately, but mine are a little different. I always encounter Soldiers that just use ZPG when Peashooter uses Pea Super and win, because the hit box of the damn thing is so broken.
I would like Foot Soldier’s Rapid Fire upgrade to remain as is, maybe even buff its speed to more than it provides now, however it should cost 4 upgrade points to use, reduce his damage and increase his time to reload.
