Interesting that I saw this post as my bro and former teammate called me two days ago to discuss this very topic about a military sniper course he is currently running. They have 18 shooters IIRC. 12 have Nightforce/S&B/Bushnell HDMR's and 6 have Leupold MK4 3.5-10x40 M2's. The twelve with the NF's/S&B's/HDMR's are rocking it. Of the 6 with Leupolds, 2 have incorrect tracking. Almost all of the systems (M110's) are brand new with new Leupolds. The other scope are not new. This is almost exactly the "failure" rate that we see played out again and again with Leupolds. Not that all Leupolds have issues, or that they won't hold zero, but it is rare to see a Leupold hunting variable (the variable MK4's are nothing more than rebadged hunting scopes) that do not develop some issues after relatively light use.
If you want a Leupold that works get a fixed power Ultra M3A/MK4, MK 4 34mm, Locking turret, 6.5-20x50mm, or a MK8 1-8x. Initial testing seems to indicate that the newer MK 6's are doing well.
I do not have enough time on, nor have a large enough sample size to comment on the VX-6's. The one 1-6x24mm I had tracked very well for around 3k rounds of use. My buddy has it now and it is working fine.
