I am a fan of the semi auto platform for precision shooting within the capability of the cartridge it's chambered in. I shoot a 308 AR, it's one of my favorite rifles to shoot. It has a 18" Rock Creek 5R barrel and with a can it's very enjoyable and capable of the accuracy needed to get consistent hits out to 650yds.
Beyond that, I would move probably move to a magnum bolt action. I live in WV, where finding a clear shot beyond 650yds is not so common. Shooting 650yds here, 800'-1000'ASL in 60-80%+ humidity with thick forest and vegetation limiting shots makes it a challenge vs shooting wide open shots at high elevation at the same range. So for me, in my area, it works perfectly. To folks out west that isn't even considered long range, more intermediate.
So I think they have their place. I've never fired a Nemo Omen. They are chambered in cartridges that have the ability to get to longer ranges. I've found that semi autos limit the load due to the gas system. But I am a believer in the AR platform when built properly, can produce the accuracy to get out there. So I vote yes...