I have Leupold Wind River 10 x 50s and think they are great. I had the opportunity to check out both Kahles 10 x 42s and Swarovski 10 x 42s with my Wind Rivers under long distance and low light conditions on a Montana hunt in 2003 and must say there was very little difference. To be fair though, the 10 x 42s were much smaller and lighter. The Wind Rivers are pretty rugged though.