Oh, thanks for getting me onto KindleGen, Pdurrant!
I've started using it and its really useful. I created the html as XHTML Transitional Charset UTF8 and put in named character entities. The KindleGen output seems to read nicely, so hopefully the characters don't prove troublesome in other readers?
A part of me keeps thinking: use numeric entities. But I read once that older kindles have trouble with numeric entities--don't know how true this is?