Haven't, so no hard "comparison" results to offer — but Gambits libs are included in Gerbil and readily importable or some of them (maybe all? dunno) auto-imported, and Gambit is Gerbil's compilation foundation essentially AFAIK. Where it differs from or expands upon the Gambit basis is "our own macro expander" (haven't particular gotten into that area of understanding yet tho) and the extremely-modern-real-worldish stdlib (http, json, actors, db driver bindings etc), perhaps other aspects too (ie. might cover further SRFIs beyond what Gambit does, dunno for sure though; ie. the FFI might be beyond Gambit's or not, again I wouldn't know).