Do not take your sightron scope scuba diving .... While it may be possible to swim out of the airlock on a submarine with your nightforce nxs, i can assure you it will not work with a sightron... (what about a NF br ?)
Today I shot in the rain all day and the sightron is slightly fogged inside the front objective and will require a day on the window sill, i expect. This may account for the $1500 price difference between the two
I use a NF BR and also a Lynx 20x42, which is what I used during the 2011 Queens, the two days of the Macintosh in the rain, the three days of the Queens with the NF BR. My next scope will be the NXS to solve this problem as Malabar is prone to this, let alone anywhere else.