Most 50i/60i cameras average the even and odd lines for an extra 6db of gain in interlaced modes. Does the EX1 do this as well?

Yes, the EX1 does the 2-line averaging in 1080i modes. Apart from increasing sensitivity, this also reduces aliasing and flicker effects caused by interlacing.

By the way, on my old Betacam (a Sony DXC-537AP dockable camera), there's a switch called EVS that disables line averaging, which, know what? bingo! It increases vertical resolution and drops sensitivity by one stop. But the footage generated that way causes a such a noticeable flickering on sharp details that I have never used it (except for getting a sharper image of the resolution chart when adjusting the lens back-focus, it was best adjusted when the lines most flickered!).

I don't know if the EX1 has a similar setting to disable averaging, but the resulting footage will suffer of the same flickering than in her Betacam grandmother. Maybe it will be less apparent in HD than in SD video, the only way to know is experimenting (if an EVS-like setting exists on the EX1!).

Thanks for confirming that.