I'm about to remodel the shower and am thinking of replacing the old valve
with a pressure balance valve. Is an anti-scald valve the same as a pressure
balance valve with a hot water limiter? Why is the limiter needed? If the
water is too hot, wouldn't it be better to lower the temperature at the hot
water heater instead of restricting the hot water at the valve?

Is there any reliability issues with these valves?

Some of these valves have only one control that increases both the waterflow
and water temperature, apparently the waterflow is increased to the max very
early on and subsequent turning of the handle adjust only the ratio of hot
water. I prefer being able to adjust both the temperature and the waterflow.
But looking at the spec it's hard to tell if it allows controlling both the
temperature and water flow. How do you tell?

E.g.
http://www.homedepot.com/prel80/HDUS...cm_ite=froogle