RE: OZ. VS SPEED
Go with the better of both worlds. Higher velocity and drop down in shot size. If you are using BB or BBB drop to #1s or #2s. Take a lesson from the turkey hunters. The difficulty to kill a turkey is about the same for a goose. Turkey hunters are only concerned with head and neck pattern density. You'll never hear them talk about effectiveness of body shots. The most popular shot sizes for turkey are #4-#6s. So, just like a turkey, concentrate on more pellets to the head and neck.
More than anything though, get in front of the bird. You may think that your aim is good because you are blowing feathers off their tail when in actuality you need to be 12-24 ins. more in front. Believe me, I am talking more about myself than you. I am constantly reminding myself to do this.
Bottom line, I have been killing geese more successfully since dropping shot size for more density and increasing lead.