For what it is worth, I have a single shot 7x64 falling block; it is a great chambering that is easy to feed and can do pretty well do 90% of anything you need a hunting gun to do. I could be criticized as non-traditional for having the rimless version of a cartridge in a single shot but it made sense to me. When I got the rifle there was quite a bit of 7x64 factory ammo floating around Canada and plenty of brass to had. At that time, it was a real challenge to find 7x65R, brass or ammo. If most break action or falling block single shots (K95, K5, Hagn, Jaeger 9, 1885, No.1, etc) can reliably use rimless cartridges (I am sure Blaser wouldn't chamber 30-06 in the K95 if there was a real issue with the extractor slipping the rim), the availability of rimless ammunition and brass is superior, and, when you do have rimmed/rimless versions of a cartridge, the rimless factory ammo is loaded (or closer) to it's full potential, I can't see the utility in rimmed cartridges when you have the choice.
However, by a strange turn of events, I do have set of 7x65R RCBS dies that need a new home, should anyone need...