I have the 600, not impressed I don't think it picks up anything past 300 yds! Got it for Christmas so I didn't get to try before you buy. I mainly use it for bow hunting here so it's ok, but would suck for out west.
The Leupold I had was worthless past 300 yards too and was no better then the cheaper Bushnell I already had. I got it for christmas too and took it back to Cabelas and traded it in on the Leica. Kinda felt bad returning a gift but really seemed like a waste to keep something that didnt work any better then what I had too.