Hey, I just wrote an awesome thread and it closed, so heres the summary:
Which is the best camera available for P+S rugged cameras?
Is there any notable difference in the WG-3 over the WG-10?
The one - huge - difference is the f:2.0 lens. It means going from daytime-only camera to daytime-and-twilight camera.
Does anyone have one that can comment on its picture quality (main POI is contrast and colours)?
Don't know - my experience is with Olympus TG-1.
Still, in the same light, you'd be shooting the WG-3 with a 2-stops lower ISO setting than the WG-10. That should tell you pretty much all you need to know.
Its primary function is snow and water sports, possibly low light/night shots but I know they'll be grainy so where ever possible I'll have an SLR instead. I had thought of Go-Pro but I don't wear a helmet so its kind of redundant.
Don't they make chest mounts for GoPro?