Do you mean a radial mounted master cylinder or caliper? In both cases they accomplish similar benefits which is adding feel. The benefit of the radial mounted master cylinder is to have the hydraulic and mechanical forces in the same plane, I added one to my zx6r and it did indeed do that, you can also get different ratios and cylinder sizes which dictates the amount of force given to the brakes.
Radial callipers came about to reduce the twisting on the calliper by mounting it at both ends.
An upgrade to 4 pot callipers would provide the best upgrade as long as the master cylinder has enough pumping capacity as with 2 pot sliding callipers it’s effectively the 2 pistons pushing against the body of the calliper rather than 2 opposing pistons.