The scale protection thing is a national code, so unless modified by the local authorities, I doubt you can legally install one. Some of the people here are not thrilled with PF, either. I have no personal experience.
Pressure-balanced valves I'm familiar with do not have a volume control. To get a volume control, you need to step up to a thermostatic valve. But, those are not single handle. From personal expeience, a thermostically controlled valve is a pleasure to use, since you rarely change the temperature setting, and you have only to use one control for volume. Some of them use a small lever for temp and a bigger knob or lever for volume, so you get nearly the same operation.