Deane,
I've been very interested in these libraries, but so far they are all too physics-centric for my taste. Also, I've been totally overwhelmed, so I haven't had the time to look at your library at all.
I think I took a look at an earlier version and commented favorably on it, though.
You did - in fact, it was you that encouraged me to push implementation of heterogeneous operators in this library. I understand the overwhelmed phenomenon - this code sat for three years in stasis before being exhumed... Despite being a physicist myself, I've tried fairly hard to make this library as general as possible without compromising performance or ease of use. I guess time will tell if I've succeeded...
If I ever find the time, I'll take a look and comment. If you dig through the boost archives, you'll find lots of comments by me about what I'm looking for.
I do hope you manage to scrape together the time to play with it a bit. I know how valuable time is, which makes the whole Boost/open source enterprise and its successes all the more surprising to me. You were quite active in earlier unit/dimensional analysis discussions, and some of your suggestions certainly helped to shape the interface. At this point, it should be fairly mature and mostly self-explanatory. I'd love to hear what you think. Regards, Matthias