Holy crap! That stuff's $1.50 a pop... Won't be shooting a lot of that.
But of course it comes with superb Lapua brass so at least you have something to reload.
I don't doubt the long range numbers on the .260 a bit and cartainly if you shoot a good deal at long range the reduced recoil helps as well.
But at the end of the day there's no magic long range bullet/cartridge. Shooting at 600 and beyond is truly a game of skill and no ballistic coefficient or velocity delta will save you. You either know your come ups and wind dope or you don't. And it really matters not a hill of beans if you have to add 12 clicks right windage and I have to add 15 at 800 yards You either dial it in or you miss. Same with come ups.
At 1,000 yards a top Palma shooter with 155 grain bullets and iron sights will outshoot a novice shooter with a Nightforce scope and a .260 Remington with 142 grain match bullets all day long. I've seen it with even more experienced long range shots.
Truly the equipment can give you an edge. But it won't win the day.
In truth--if you have "work" to do at 1,000 yards (not just punching holes in paper) you will be beter served with a larger cartridge like a .300 Win Mag or a .338 Lapua. There's no substitute for mass when it comes to really getting the job done WAY downrange.