BigHammer

Yes, I shoot my .450 more than most of my other rifles, and I think I handle the recoil well by now. (I still hate to shoot it from the bench though...) I do not like muzzle brakes, and will not fit any on any one of my rifles. The key to shooting big bores without flinch is mental conditioning. I believe you can do it by telling yourself that the rifle cannot hurt you, and of course lots of practice. BTW, before I went out to hunt with it the first time, I fired more than 150 shots on the range. I like to use a fullsize buffalo target for practice, and had to draw one when I started out with the cartridge. Luckily, the SA Hunters and Conservation Assosiation of which I am a member, brought out a very realistic 3/4 color target which is great for practice. I normally put it up at 50 yards, and then dash around it from the firing line. On reaching the firing line again, (the adrenalin and my breath racing), I fire 3 shots at the target. I try to keep time to fire these shots under 6 seconds.
Whichever one you choose between the .416 or the .450 Rigby, as a hunting client, you will be very well equipped. I chose the .450 for extra insurance