[Stephen Neal]

50Hz to 100Hz processing is far from trivial, especially if you are also trying to interpolate missing fields/frames from 25Hz sources (or 50Hz sources in some cases). The 50->100Hz conversion on SD displays has never been of a particularly high quality - and I know of no broadcast professionals who take picture quality seriously who would consider viewing on a 100Hz display.

The amount of processing required to do it to a high quality - which is what you'd want on a high resolution LCD or Plasma - is not insignificant, and is more onerous than de-interlacing - especially if you are trying to interpolate motion to give a "smooth" look to sources.

Given that the de-interlacing in most panels - even high end models - is pretty basic, and doesn't maximised the picture detail present in an SD or HD interlaced source (when carrying interlaced source material rather than progressive) - I'd steer clear of any additional processing overhead.

(For reference - the highest quality de-interlacer and upconverter I currently know of is the S&W Quasar - which is a spin-off of their Phase Correlation 50<->60 standards converters. This is far from cheap - and makes consumer level scalers look like toys.)