Marc, I just realized that Gambit is case-sensitive by default! The Gambit manual node "Runtime options for all programs" says:
The `s' option selects standard Scheme mode. In this mode the reader is case-insensitive and keywords are not recognized. The `S' option selects Gambit Scheme mode (the reader is case-sensitive and recognizes keywords which end with a colon). By default Gambit Scheme mode is used.
I'm reading that right, aren't I? "By default Gambit ... is case-sensitive and recognizes keywords which end with a colon." I don't think you should bury information like that!!! I'd put it on the 1st page of the manual!
It's a big deal for me, because I have a lot of case-sensitive DrScheme code. I've been making the code case-insensitive, which is a pain, and fraught with peril...