Seems like you need to compare apples to apples to figure out your question. There are plenty of low pressure rounds that are no fun to shoot for an extended period of time.
You should compare same caliber, bullet weight, velocity, and gun to get some idea. Something like the .223 vs. the swift loaded to the same velocity. The swift will have the lower pressure, but will it be the more enjoyable round?
I think rounds that burn less powder and have lower velocity are probably the more enjoyable factor, not what pressure they operate at.
