let me start out by saying I am a vortex customer for life, not only because of their great products but because of their great customer service I have nothing bad to say at all.
I did have a pair of these but got rid of them after my latest Montana Hunt.
Cold weather definitely plays a huge factor. Both me and a buddy had the exact same issues of two different pairs of the old furys. Ambient temp was about 15-20 all week with wind chill at or near zero. During those temps we could not range anything past 200 yards. Called Vortex and learned that the engineers were unable to get the needed power out of the batteries below 15 degrees which would affect the capability of the unit.
I was assured that the updated furys the issue had been resolved and that the ability of the unit to function in cold weather had been greatly increased.
Other that that issue if you know you won’t be hunting in those temperatures the furys are great. The glass is very crisp and the speed of the range finder is decent speed for the price point.
Again this was just my experience with the first gen furys.