First, it's not recommended to use static linking on Unixes (like OS X). There might be something subtle here with the compilation flags too.
Can you gather more information about the crash ? Use a debug version of SFML and print the VM for example.
Finally, get the last sources. Maybe it won't change a thing here but I prefer to be sure that it's not an bug already fixed somehow.
EDIT: Ho, and, BTW, you never told me exactly how you modified SFML to use GC. Maybe the issue lies here.