Re: how important is ARC?
If the CRF gives you the slope then I think I would go that route. The 1600B bc part is only good for 500 yards anyway. I do think it is a nice feature and if you have it set up correctly will give a good results for a quick adjustment. For example, if I input a ballistic selection close to my DOPE I can range anything to the 500 mark and get a solution that will be accurate for hunting. This will take into account, ABP, Temp, Slope, Range, and bullet drop. I can set the unit on MOA and it will give me a MOA solution to dial on the scope.
I failed to test it this weekend, just flat forgot. I need to set the unit on a BC program and see if it still ranges past the maximum solution yardage. For example I ranged a group of rocks at 1982 yards on the standard setting. I am not sure if it will do that on the BC setting.