>but since you're working from a master-file, you should not
chain your conversions.  instead, write mobi-friendly .html.
and feed _that_ to kindlegen.  separate it totally from .epub.

You are better off making a “mobi-friendly” version of your epub, since that will support more of the “advanced” features of Kindles automatically, such as navigational aids.  In practice, I don’t find that Mobi8 “incompatibilities” are any greater than the myriad epub platform incompatibilities already out there.  Certainly there are some extraordinarily sucky epub implementation out there.

>don't listen to anyone who tells you that kf8 is just like .epub.

If you try it, I think you will find that mobi8 incompatibles are in practice not more or less of a problem than what you will find with the other epub platform incompatibilities.

> (and, as i said up above, the platform to shoot for is apple's.)

Seriously? Go read Elizabeth Castro’s rants about Apples’ gratuitous incompatibilities, particularly sucky implementation of fonts – and Elizabeth Castro is an “Apple Centric” developer no less.  Certainly *do* check to see how your work runs on Apple – so you can also see how Apple’s incompatibilities break your work.  While you are out it check out the sales specs for the share of commercial ebooks actually being sold on Apple – Amazon is widely reported to have 90% of the market.

>similarly, it does no good to say "i'm following the specification",
since the viewer-apps don't give a tinker's damn about the spec.
i know this is not what people would like to hear.  but it's true.

Also a true statement about HTML in general.  No HTML browser actually implements the spec.  What the major browsers have done is work together over the years to reduce incompatibilities in what they do implement.