I have never heard anyone complain about the performance of .416 Rigby. Factory loads are lower pressure than the Lott and that is an advantage in hot weather that hasn't been mentioned so far. Since reloading is an option you can increase velocities by up to 200fps or reduce the loads with lighter bullets to make clean kills on deer, moose or African plains game with minimal meat damage and a reliable knockout punch. What the Rigby gives up to the .458 in diameter it makes up in penetration. Truly one of the greatest classic British bolt action cartridges.
My .416 Rigby is a CZ 550 Safari Classics American with fancy grade stock. Talley QD rings and a Leupold Vari-X III 1.5-5. I can load 450gr Woodleighs out to a COL of 3.8".