In my experience if you get a demo one and it is 100% operational, and you run it through the paces for 60 or so days without a hiccup it is good to go. No reason to spend 35% more for a 4 year warranty
Be sure to test them out in cold weather, I found out mine did not work in the cold weather after having them for a year and a half on a late November Colorado deer hunt, previously I basically used them for archery and early rifle hunts (when its usually above freezing) My binos were sent in 1st of January haven't got them back yet.. Glad I had more than a year warranty.. Other than cold issues, binos are AWESOME!!! cant wait to get them bsck..