Alex and Joel,
I have been using the text-based debugger in Gambit for about 6 months. I know about ",s", ",e", ",b" and friends. I have dug into the Gambit code and am using the underlying functions to connect these facilities to the Eclipse debugger GUI. Gambit is reasonable in this respect, although the lack of breakpoints is annoying. I looked into other versions of Scheme, and as far as I can tell Gambit's underlying capabilities for debugging are better than most. But I'm tired of typing commands, and I'm tired of copying variable names so that I can execute them. I'm tired of writing my own inspectors to get views of my objects. This is all much harder than it should be, and in the long run it reduces my debugging productivity significantly, over using a good graphical debugger. To me, a REPL is not a debugger. Maybe 20 years ago it would be acceptable, but not now. I'm willing to put up with it because I need to use Scheme. I'm specifically talking about debugging here, not other aspects of the development environment.
I can see that there is a culture clash here. I know I'm representing a view that is a minority on this list. But I'm looking at Scheme from the outside, and this is how it seems to me.
William