I have the Nikon Buckmaster 600 and a Leica 1200 CRF. The Nikon does a pretty good job out to 500 or so but will not consistently range game sized targets much past that. All in all it is a really good rangefinder for the money and has been a really nice unit for bowhunting.
The Leica speaks for itself, I have been amazed at the clarity, compact size, and range that it has. It is definetly one of those expensive purchases that you really don't regret after you get it out in the field...