You’ll need a real HD monitor to see the difference in the de-interlacers. FCP doesn’t show interlaced video right, so it’s going to be hard for you to tell. They all look subtley different.
For 50i to 24p, you need to de-interlace, bump the video to uncompressed, and use cinema tools to conform. That’s the best way.
Graeme
– http://www.nattress.com – Film Effects and Standards Conversion for FCP