> I have relatives who pronounce "pen" and "pin" identically, and are generally hard-pressed to hear the difference in how I pronounce them. On the other side, I also have relatives who distinguish between "ferry" and "fairy", which I don't.
Yes, some hard choices do need to be made. In cases like these, it’s almost always better to err on the side of preserving distinctions even if the speaker does not recognize the distinctions. Because over time, they will start to recognize patterns and understand the distinctions more while nothing of value is lost in English.
> Shavian might still require you to use more than one letter for the same sound (and therefore have to remember which words use which)
Yes and for the most part I think this is a good thing. It is a very small concession to make considering the alternative.
> Or, at least, it will if you want to have standardized orthography.
One single prescriptive spelling for global english may be impossible for the time being. But I am very interested in further researching a kind of neo-mid-atlantic accent.