I've been playing with the line spacing in the Modified Charis SIL fonts and I have made the spacing even tighter then the official Compact version. This looks pretty good in Mobi and KF8. It actually seems to fix the spacing issue with KF8. The font name is now called Charis SIL Compact in order to denote it being different. The filenames are the same as before. But that is something you can easily change if you want.
I'd like opinions on how you think this looks. The link is for the fonts including the smallcaps (for KF8).
http://www.mediafire.com/download.php?64cse2dshispx08
P.S. If you've downloaded the Charis SIL Compact from the SIL site, don't bother with them. You will find them not as good as the modied version linked above. The Modified version has a smaller line height and a greater weight.