I'm still perservering with Gambit scheme, and progressing pretty slowly it has to be said. The first thing I've been missing is the lack of refactoring tools for scheme.
I wrote the basic python refactoring functionality in bicyclerepairman a long while ago, and having it as part of my daily toolset has strongly influenced the way I program. For example, I tend to follow the 'bash out some code and then clean it up' style of development. In particular, I have a habit of naming variables and functions badly and then renaming them later as I code.
So my initial thought is: no problem - I'll just knock up a bicyclerepairman for scheme! The problem is that I'm not quite sure how to do automated refactoring with a repl. You see Python has no real repl culture (sure it has a repl, but nobody uses it except for trying out simple expressions). People tend to run their program/unittests from scratch each iteration, which means the entire environment gets re-evaluated on each run.
The challenge with running a repl while you develop is keeping it in sync with your refactored code: E.g. if I rename a function that's used in multiple places, that results in lots of code that needs re-evaluating. Can this be done automatically (e.g. could it be made to work by just re-eval'ing files?). Hmm.. I think I need to talk to somebody with a lot more scheme experience than I have. Unfortunately I don't actually know any experienced schemers, especially not in London or Birmingham; maybe somebody from lshift can help?