I was told this straight from a Panasonic Rep.
The S1, G10 and V10 models all have the exact same panels in them. The differences are in the video processing (G10/V10 have THX mode, S1 does not). If you choose to have the TV calibrated and bypass the THX mode, they will all look practically identical. If you choose not to have them calibrated, the G10 and V10 will look better when watching the THX mode.
Other than that the differences are things like, more inputs, Vierra Link, netflix, stuff like that.