If the camera doesn't do a progressive picture, then I ofcourse shoot in 50i, but I always deinterlace in post. I just don't like the look of 50i. 25p is so much more film like motion, in my opinion. And if I had the money, I'd shoot everything on film.

Confusing thing with these shutter speeds is the unlogical way that sony marks these speeds with their cameras.
With miniDV 1/50 means per field and 1/25 means per frame.
With eng cameras 1/50 per field is marked "off" and marked 1/50 means per frame.