So...
I got my Kindle today. After a few tests, I decided to go with the KFX output plugin. I prefer the text to be better justified and hyphenated. And 4 gigs is still a lot of storage.
Strange enough, some converted ePub are smaller in size in KFX. Most are bigger though.
One converted ebook in KFX would not play nice with Amazon's Enhanced Typesetting. But so far, it's the only one.
Thanks for all your help.