1. Doesn't crash in Panther (at least, not in my experience)
2. It does a good job of repairing fonts... but some of the other features may conflict with Extensis Suitcase, if you use that: what I have experinced, removing unnecessary bitmap sizes from a font might cause suitcase to display an error with the fonts printer file, of something like that... Also, combining multiple fonts from the same family into one file (for example, Univers Regular and Univers Extended suitcases into on "Univers" suitcase) caused certain fonts to act weird in suitcase, but these are all problems with suitcase. Editing the font suitcase files manually in OS 9 (not classic) remedied all of those problems.