Carey,

We do have a thermostatically controlled mixing valve for the shower. That was the best upgrade I made. Ruth thinks it is the best thing since sliced bread. I will say that after a long day of driving in warm weather the shower was "warmer" that the setting usually delivers. I think the hot water was hot and the "cold" water tank was warmer than usual.

But you are right. That valve is great. A bit pricy but well, well worth it. I am going to plumb it to the bathroom sink as well as sometimes the water gets hot quickly. (My installation did away with the divider valve.)