I read this somewhere, but maybe i am confused or reading it wrong.
"If you get a 50hz set rather than 100hz or progressive you'll be able to make use of all the lightgun games which normally only work with 50hz sets. Also 50hz sets have absolutely no input lag as they do not process the image so game response time is far superior to lcds and a lesser extent plasmas.
Many 50hz sets have a true RGB mode which gives fantastic results. 100hz sets can't do this as they have to videograb the incoming video to process."