Redline fluids protect, Im sure, but they never seemed to maintain feel from experience in my 91 318i.
Examples: 4.10 LSD in the car - always had a bit of a whine on the highway. Redline (75w-90 and w-140) would make it go away for a little bit, but it would slowly come back in time. Moving to Specialty Formulations diff fluid fixed it and it has never come back.
MT, specified for ATF fill. Redline MTF would feel real good at the start, but give it about a years use and it would get much harder to engage into first gear in the cold, and sitting with clutch in, shifter in gear, there was a lot of noise from the MT. Switching to Amsoil MTF 5w-30 type made it go away and has stayed far more consistent.
So Im not saying that redline stuff is bad, I just think it is geared towards track and enthusiast use where the miles wont be high and the change-out will be often.
Now, is XO or XJ the right diff fluid for your car?
I dont have an issue going with XO, but would also consider Amsoil SVG in the 90 or 110 versions (or if XJ is required, then 140), and would also consider M1 right off the shelf. We have done well with M1 and RP gear oils in various diffs that have very high (>200k) mileage.