I had the x50 and sent it back for the x200xp.
What I like about them is that they take AA batteries: NiCD, NIMH, Alky's, and Li-Ion. If you have the external power adapters, you can charge the rechargables in the units.
I should state that getting the external power cord, and the video output cord was a bit of a PITA. Also that the video output in only RCA (aka standard definition "yellow" jack) compatible. (NTSC?)
LEOs have been using them mounted in the open windows of their cars and using the video output see what's going on in wooded area, etc. (There are probably better units at this point, but the Thermal Eyes are very rugged.)
The need for manual focus is a bit of a PITA, but it works well enough.
With Li-ion batteries, it lasts for a considerable time...
Interestingly, if you are surveiling an area, something to consider might be a FLIR i7 unit. It's got a large screen, and it auto-adjusts for ambient temperatures... basically, it's everything you need to make sure you know where something is.
I buddy of mine, a retired USA SF Team Leader, pointed the FLIR i7 out to me after playing with the X200xp. His comment was "the unit is fine if your are the hunter, but not so much if you are the hunted" - due to the lack a wide FOV close up.
Conversely, the i7, while in industrial tool, is fine for hunting, has decent digital zoom, an adjustable FOV, and generally costs a fair amount less. What I was impressed by was the ability to take a look at ambient heat in the area and readjust on the fly when you were going to get heat wash (similiar to looking into the sun, or driving toward the sun).