If you get the chance, go to the Dallas Safari Club or Safari Club International's convention(s) next month. There you will be able to see and handle many different DG rifles. You may also be able to get stock fit which in my mind would be a plus. Also check and see the magazine capacity of the rifle, some rifles carry three rounds while others carry four. In a control feed rifle thats your limit while with a push feed you can add one in the chamber.
Of the .416 Rigby rifles that I have handled I prefer the Heym, Mauser 98, Rigby, Sako 85 and then the CZ550 in that order. I own the CZ but that was all I could afford at the time. Currently I'm shooting a .416 Rem Mag out of a Blaser R8 which is a wonderful platform but not available in .416 Rigby. If you can afford the $12-14,000.00 then any of the first three mentioned above would serve you well without regret but it does lighten the pocket. Generally you do get what you pay for in DG rifles. But there are some bargains like the Sako 85, if on a budget that's the best gun for the money IMHO, Its only downside is it's a little light for recoil. Best of luck on your search for a .416 Rigby it's a great caliber.