At your age, with your surgeries, I certainly argree that a mechanical makes far more sense, and offers you a much better future. Coumadin may be a bother, but you will burn through tissue valves at your age, and you will wind up with way too many surgeries.
Your heart has scar tissue enough, after the Ross and the other OHS.
Get one of the top, new-breed mechanicals, take a break from the scalpel, and go out and live your life. You'll do okay with the Coumadin. And anecdotal evidence says there's more "give" in INRs than most here tend to advertise. People get major fluctuations all the time without dire results. Just try to get it level and keep up with testing - home testing, that is. It will become a routine part of your life, like brushing your teeth.
The point of figuring a mortality rate is how it applies to you. The phrase "as high as" invalidates whatever follows it, so it's a pretty meaningless percentage. It's akin to saying, "savings of up to 50%!" However, Joe isn't a prime example of risk percentages either, as he has had other health issues and major surgeries as well, that certainly affect his odds.
And dying isn't the only negative outcome you can have from a surgery. You could have permanent arrhythmias, pericardial constriction, stroke, or other issues.
Best wishes,