Thinking about it.
1Oz is 437.5 grains. (7000/16)
1 1/4 ounce is 546.88 grains. (7000/12.8 ) Or (437.5X 1.25)
The 7000 is how many grains are in a pound.
I think, either moving more than 1200 FPS is more than enough for deer, pigs or black bear.
My questing back to you is are your shots going to be 75 yards?
If so shoot the 1oz slugs, no guess work to 75 yards. Just aim at the deer and bang dead deer out to 75 yards.
if your shots are going to be more on the 50 yard side shoot the 1 1/4 as the sights are there.
If you have to guess on the longer shots and hold over the deer at 75 yards..... Better to shoot the lazer of the two.