Not to forget that the 256 Mannlicher was used on countless number of plains game and of course Elephant by several big game hunters not just Bell. Before the first world war the 256 Mannlicher was the favored Rifle and cartridge of many big game hunters. A 140 or 160 grain 6.5mm bullet is hard to beat.

I have three 6.5x53R, one 6.5x54MS and one 6.5x65R RWS and I would like a 264 Winchester one day.

Having said that, I do have a Model 70 Short Action in 308 Winchester which I use a lot with 180 grain bullets. Superb rifle that shoots very accurately and is a pleasure to shoot.
I have just bought some Winchester 168 grain Sub-Sonic bullets to try as I have a property that I can shoot on which is in a bit of a built up area, so hopefully these will be a lot quieter.

I do not have a lot of interest in modern cartridges, I don't hate them I just don't have a lot of interest as there are so many nice older cartridges with a lot of history which makes them fun to shoot. IMO.
However if I was to buy a rifle with a modern cartridge it would be a 6.5 Creedmoor. It looks and sounds pretty sexy and it is a 6.5 after all.

Matt.