OK, I'm going to lay a little bit of technical knowledge on you.
First, the proportioning valve is pretty much a spring loaded valve. Here's what happens and why. When you press the rear brake, a pressure is built up. This pressure and fluid volume are immediately applied to the rear caliper. Actually, the pressure is a result of first the fluid reaching the rear caliper, and when it moves and bottoms out the pressure is built up. As this pressure increases, as soon as it reaches the spring rate pressure it opens the pathway to the front brake and allows fluid to be sent to the front caliper. The reason for this is so that the front does not dive when you hit the rear! The rear brake is applied prior to the front brake being activated! It's a safety feature.
Now the metering valve is just a fixed orifice! Its function in life is to regulate or limit the volume of fluid per second so that the front brake does not feel a bunch of pressure and volume instantaneously. Yet another safety feature to ensure smooth even braking on the dual braking system.
To answer Condor's question, no, the front brake is not really metered as it is independent of the rear and your finger squeeze, which is a lot more sensitive than a foot stomp, is used to regulate the force of braking...