I ended up buying both the Leupy Mark 4 and the Bushnell 6500 2.5-16x42 mil-dot so I could compare them side by side for myself. Never even mounted the Leupold, the Bushnell was hands down the better scope. The glass was clearer, the contrast sharper, the reticle darker, and the overall quality more impressive. It's been on a 300 WSM for about 4 months now and no problems to report.
Ended up replacing the Mark 4 with a Sightron Big Sky II, another really impressive. As soon as I get a free afternoon were the weather cooperates I will put together a side by side comparison of the two. Nothing against leupold, I have owned a number of their scopes and still have one, but I'm finding that the competition has caught up with (and even passed) them quality and price wise.