Battle is correct on shot charges- more is more all else considered. An ounce and an eighth of shot at 90% will put more pellets in the circle than a one ounce 100% pattern. An 80% pattern will have more pellets than a 7/8 oz load will hold. This can readily be seen on the patterning board though one may have to actually count each hole rather than just look.
That said, I load 7/8 oz of 8s as my primary target load. That charge weight I find adequate for the majority of my shooting. Those targets that don't break are seldom the fault of my equipment. I can live with the occasional escaped clay.
This is also the most economical when reloading. Though it is only a half a dollar cheaper than the least expensive 12 ga loads at today's component prices it is half that of comparable factory loads- when one can find them. Depending on the number of rounds shot per year, the savings can be considerable.
The recoil is also very mild in a 9.5-10# gun. That reduces the possibility of some shooting related injuries which was a concern when I was competing and firing 15,000 rounds a year.
There are compelling reasons for and against to use the various charge weights and one needs to weight the arguements for themselves. There is no perfect choice and that choice could easily change given the circumstance.
