Sorry, I forgot to reply. You race with a controller...I do not. That plays a little into tuning since there are things I do with the wheel that you will not do with a controller. I have tried rear biased brakes on several occasions when I first started to learn how to tune and combining them with a wheel never worked. My first experience was with the Ferrari 512BB at le Sarthe. The car would spin out braking at high speed.
Weight transfer is going to occur no matter what your brake settings are. If you were able to run 0/10 in a MR you'd have extremely long braking distances because the more you brake, the less weight there will be on your braking tires. Furthermore, as your rear tires began to overheat, they would have less grip than the fronts causing oversteer the second you turned the wheel. There is a reason all cars have larger front brakes...even rear engine Porsches.
The game models grip via two parameters, temperature and tread life. Lateral and horizontal grip increase the tire temp equally, so if you build up too much heat during braking, you'll jump to the next grip level during the turn. Even if the tire stays white, there are varying degrees of grip before the tire turns red.
For an MR car, reducing a 5/5 balance to 5/4 stabilizes the rear end because it reduces the amount of heat built up in the rear tires during initial braking, giving you more headroom for holding the additional rear weight when you make it to mid-corner. I went one step further and ran 4/3 to ensure I wouldn't burn up the tires under braking. I don't think my tires went red once.
Exiting turn 2, the corkscrew, and the final turn, my car was completely planted. The only oversteer I saw was when I lifted off the throttle mid corner. Rainey curve was the culprit. I would rarely brake on that turn and just coasting could cause the rear end to step out.
For a FF car, running higher rear bias like 5/7 works due to the same tire temp principle. Rear tires will never heat up enough in the corners to provide optimum grip, so increasing the rear bias will induce abs lockup and pump a little more heat into the tires without any affects on stability. Plus, if you begin to understeer, you can tap the brake pedal under full throttle to get the rear to step out and adjust your line.