Hmmm, not sure how a metering valve differs from a proportioning valve
In fact both of those names could be used for a standard proportioning valve, it both meters flow and differentiates pressure
What does the "pressure differential switch" do? I assume it dynamically changes brake pressure to the wheels with zero driver input? Kinda neat... I'd be interested to know what it does though, not just what its called
Land Cruisers never had such a beast (well not on the older units anyhow, newer ABS models have all sorts of features). The do have a LSPV (load sensing proportioning valve) that changes the rear braking based on the load over the rear axle, seems to work fairly well for stock vehicles, its often ditched in place of a manual valve in a build up.
While I can agree with not removing a safety feature... many times they were designed for just the stock vehicle, lift them, load them differently and run far different tires and suspension and they might become an unsafe feature