Just picked up our Precept 31 UL last Wednesday. Maiden trip over the weekend. We each had very comfortable showers and no extremes hot or cold. I was so skeptical of this system, I had it written into our contract that if we didn't like the system, the dealer would replace it with a 6 gallon tank heater. We're not going back to the old system now.
Our dial is set at the coldest setting and we modified the flow with the faucet therefore keeping the temp comfortable. Even with the hot faucet on full, no negative consequences. 4 showers and no complaints. I think the key is very slight changes at the faucet until you have the settings you want. But then, I am still experimenting.
I understand the earlier model had some problems. We have the updated model with a dial in the throne room.
Good luck, Darrell