You don't have to switch to manual brakes, but you should replace your master cylinder because it's a drum/drum master cylinder. I use 15/16" bore manual master cylinders on my cars, they give a little more pedal travel than stock so not as hard of a pedal to deal with. Plus the little bit of additional travel improves pedal feel and brake control, at least in my opinion.
There is a benefit to the 11.75" kit, more stopping power and better heat dissipation. They're still all stock parts too, used on the later B and R bodies. I've had them on my Challenger for like 70k miles, they work well and are a nice upgrade over the 10.95's. The do require 15" wheels though, 14's won't work so if you have 14" wheels that's definitely a consideration.
