I'll type what i can until the wife hollers "Let's go!" Church won't wait on me.
Disclaimer: It would be a long answer to answer your question but I would like to state in general I am not familiar with those ratio's you cite.
Sam Maloof, considered one of the premier genuis's of woodworking had alot to say about the handcut dovetail and he was not in particular a fan of strict technical protocol.
Remember that the more meat you give one, the less you leave for the other. Aesthetics are certainly a consideration but like you I always try to consider the service life of a piece as being in therms of generations not years.
Take a good look at a piece with doevtail joints and study the ratio of the pins (especially the inside flare) to the base of a tail. The pins, in my thinking, can afford to be smaller becasue they don't have all that "wing" on top and bottom like a tail, that is prone to chip off if you aren't careful, and the grain orientaion works so much in favor of the pin. i like the look of smaller pins on long joints and the a more even look on shorter ones - in general.
i have seen few dovetail pices i didn't like though.
i prefer handcut because it looks better to me even though properly cut, it's hard to tell the difference between hand cut and jigged Dtails.
I think you should throw out the strict ratios and study the furniture itself, and gain an appreciation for approaching the piece with the idea that you are going to determine the ratio's with a view towrard common sense.
i realize "common sense" is not so common and in woodworking that can get you in trouble, I would just not be too concerned about strict ratos.
The biggest danger I see is in leaving too little meat in the base of the tail, and forgetting that pins and tails are after all, wood. And wood shrinks and it expands. Choosing your proportions, the specie for the particular design, the moisture content of the wood when the piece is asembled, and considering the service envrionment of the piece (determining what the average yearly EMC will be) are paramount to achieving the balance between function, form, and longevity.
My wonderful bride just said said "Get it in gear!" :D