They seem to be well liked and a good cost:benefit ratio being an affordable bonded bullet. Go for it. I have only used a 308 Factory load to take one hog, but it was a pass through right on the shoulder. Dropped where he stood. Close range though, 50yd.
I'm curious how fusions compare to say accubonds in jacket thickness or general "hardness"?
In general I'd choose a 180 over a 165 for elk with anything but bullets that take a lot of speed or dense tissue/bone to expand. No reason a 165 wont work great in most circumstances though.
I have used 165s in mine for 20 years- Ballistically perfect selection imo. I'm personally not a fan of the fusions but they work. They will have similar velocity and terminal performance to the old corelocks. Not bad but leaving a little power on the table. Inside of 300 yards, the elk sure won't know the difference if you do your part.