I installed a new 8" dual this weekend and it works great, no more problems with dragging brakes.

There's not much difference between a 7" and 8" when just slowing down but there's a big difference during an emergency stop, the 8" requires less than half the pedal effort. The 7” did not respond to pedal input as quickly it’s kind of sluggish, I’m not sure all applications would be the same at least in mine the 8” is a better choice.