Dan and Kika of Sailing Uma themselves recognize that this setup is not for everyone. Here's an interview with them on Sailing Ruby Rose on the subject:

* https://www.youtube.com/watch?v=xOAXi5huV1U

A better solution, for the time being, may be what Rebuilding Tally Ho is doing and use a hybrid engine:

* https://www.youtube.com/watch?v=xohxmwPfctg

He specifically chose a Beta Marine (marinized Kubota) diesel that has an electric motor/alternator connected to a 48V battery bank. If either the mechanics or electrics go, he can use the other. For short jaunts, like in and out of harbours, he can use the electric system to preserve fuel. The system has re-gen capabilities under sail.

More pricey though.