Amazing the ignorance to think that a bladder tank of any kind/size is going to shorten pump run time for pumping the same amount of water.
The little tank is great for what its designed for,....less cycles saves wear and tear, and it stops the chattering that sometimes occurs during very low flow.
I personally don't like the bigger tanks, simply because I don't like the pump running that long.
Also, you don't need a "T" at the tank. You need a "T" in a main line, and a single line to the tank.
Also, the guy at lowes should have kept his other day job at Mickeys.