I've been doing some test using URW's Kernus 3.0 and... call me whatever you want but I've found that it generates surprisingly good spacing. It's not perfect and there are always some few letters that I would space in a different way, but IMHO you can save time if in the first stages of development you use Kernus and just correct its output when necessary.
It's a pity that there is not an OS X version.
At the moment I am not using it to generate kerning because I rely more on MetricsMachine (and I like it that way).
Comments
Back in 1997–98 I was beta tester of this version of Kernus, which was the only one that went beyond kerning. It was developed for Mac OS 9 exclusively. I still provide my students who manage to get SheepShaver running with copies. We (URW++/DTL) actually never ported the stuff to FontMaster, but we’re considering to incorporate this auto-spacing (and the kerning generation) in GlyphMaster (like OTM available for OS X, Windows, and Linux).
* see also the LS Cadencer