Going out on a limb...but, yes, an adjustable proportional valve is a good idea.
However, anytime you have a knob to turn or switch to throw, there is a tendency to keep tweaking it. For a non-racing vehicle, once you have set the proportion of pressure, you don't need to mess with it again. The adjustable is better only in the sense that the factory valve is set based on a standard product.
They know how much their car weighs, they know what kind of brakes they are going to install, they even know the brand/tread design/rubber compound on the tires, then they have the luxury of being able to test the heck out of their cars and combinations to optimize everything to work together.
Having the adjustable valve gives you the ablitiy to do the same for your unique vehicle and its combination of parts and changes you have made. Just know when to quit tweaking.
_________________ "They that can give up essential Liberty to obtain a little temporary safety deserve neither Liberty nor safety"-- Benjamin Franklin
<font size=-1>[ This Message was edited by: Beoweolf on 3/27/06 9:23am ]</font>
I like the previous answer on adjustables but I guess you should be sure on that Disc-Drum master.
On a diff subject...What size are the pics you upload to this site? Also, if you change the pic it looks like it changes it everywhere, do you know why. I didn't find info on posting pics here, just where to upload them, but no details