GS500 has larger ccds, which would give you better low light video, probably better video all together.
GS500 has a focus ring.
GS500 has a 12x optical zoom. GS300 only has 10x.
There is probably more. It's just a much better camera.
I don't think either of them record in a real progressive mode. They may have a fake mode, but I'm not sure. Is that a feature that is really important to you??
I have shortlisted to these two camcorders. Would need help on understanding whether GS500 has any additional benefits over GS300 for the extra price.
Do both of them have progressive scan feature?