Pressure has nothing to do with feeding. If there was some issue with the case shape of the 375 RUger feeding, then we'd see it with the .416 RIgby, too. So if you like the way the Rigby feeds, you must agree that the Ruger will feed just as well. And the .416 Rigby certainly has a reputation as a dangerous game cartridge.
Some people claim issues with extraction due to pressure, but the H&H operates at exactly the same pressure as the Ruger. So if you like the pressure of the H&H you must like the pressure of the Ruger.
So now we ask: Does the tapered cartridge aid in extraction in a bolt action rifle? Well we have been told that for many years, but then we are back to the rest of the straight wall cartridges. They don't have a problem with extraction. So why should the Ruger?
If I was using a double rifle, or this was 100 years ago, I might be more inclined to go with a belted, tapered cartridge, but with a strong bolt action in 2011, there just isn't an advantage...Unless you want to go with the 5+1 round capacity in the CZ. You can only put 3+1 in the .375 Ruger.