To go back to the original question, lets put it like this. Why dont we use .373H&H for everything? Well, with more than enough gun we can expect excessive recoil, which will result in flinch and loss of accuracy, we can expect massive muzzle blast and flash which is not conducive for good hunting and they are more expensive to shoot.
Thanks Death from Afar, that's what I was originally wondering about. I just didn't know if in hunting situations, there are specific reasons for not using large loads -- comparable for instance to the issues of "over-penetration" when choosing HD ammo. I was liking the idea of the CZ 527 because after a few extended range sessions with my M44, something milder that would do the job just as well was sounding appealing. But since for now I can probably only swing one rifle purchase, I think the .308 will be more versatile, and I'll just get used to it.