With some help from Marc Feeley I have implemented a simple statistical profiler for Gambit. It is available at the following address: http://www.iro.umontreal.ca/~germaing/statprof.html
Here's an output example: http://www.iro.umontreal.ca/~germaing/ring.scm.html
It's not perfect and was put together somewhat quickly, but I think it can be useful.
Guillaume