A search on here will give you a lot of info, with good and bad. They seem to have a history of issues with leaky knees, but they get replaced without quibble.
I have a pair of the normal Pro Hunters and love them. There are a few good bits on both the normal ones and the X model, that frankly I would like to be able to pick and choose (a friend has a pair of the X ones)! I don't like the leg adjusters on the X, but the slope pockets are better (as opposed to straight pockets on the normal ones) - the vents on the X are useful. They are very warm and I can't stalk in them on a warm summers day.
Either way, you won't go wrong, you may cry when you first buy them but I love them.