I like my groups to be as small as possible, but on the other hand, I consider groups in the 2 - 2.5" range at 100 yards to be acceptable hunting accuracy.
When I first got into muzzleloading about 5 or 6 years ago, I was using pellets and prepackaged bullets. Accuracy was horrible by my current standards - 6" groups at 100 yards, but I didn't know any better, and plus it was better than my smoothbore shotgun I had used for many years before that. So without knowing any better, I went out there that first year and took a buck at about 100 yards. Shows that you don't need pinpoint accuracy for deer hunting.
I've shot some 100 yard groups that are about 1", but side with sabotloader in that I would rather shoot a bullet that does 2.5" groups but has superior terminal performance.