It's a Middlehurst / Rod Bell thing to remove the rear arb isn't it?
No doubt there's some proper experience behind it. But the arbs really need to be used to tune a complete package of suspension, diffs, power and 4wd setup not to mention driver preference. So for example if you run higher rear spring rates at the rear you could remove the rear arb and have the same effect as running a "conventional" rwd lower rear spring rate with an uprate rear arb.
I know Abbey like to remove the front arb based on their track experience, which goes to show there's no one right way.
Personally I have the front and rear whiteline arbs, front soft, rear hard and front 8kg springs, rear 6kg. Works nicely. I wouldn't claim its the fastest way but it feels right for me on track.