I'm glad it's working out for you, but a couple of things:
Sending un-tempered water to sinks and showers is a code-violation, even if you don't have any kids using it. (Untempered water going to dishwashers & clothes washers would be OK.)
Adding a tempering valve doesn't change the hot-water capacity, only the storage temp does. Adding a tempering valve lowers the temp of the "abandoned" water in the distribution plumbing between draws, and will in fact save some energy.
So, when you have the time & inclination, adding a tempering valve wouldn't be a bad idea.