I have a pair of Pomeranians: One goose and one gander. They were purchased as adults and are housed with ducks they were not raised with: Runners, Rouens, and a Black Swedish. Until the geese began with breeding season, they all got along pretty well.
Once breeding season began, the male did become more aggressive toward the ducks. However, he simply pinches them (if they went into HIS part of the house) and drives them away...not seriously hurt them. I didn't want the ducks to be hassled though, so made some accommodations.
Luckily our duck/goose house is built in such a way that the problem was easily solved. We made the door on the small house operable (the geese claimed this area) and put a wire door inside blocking entry into the bigger house: The bigger house has it's own entry door. The ducks like to go in at dusk and the geese when it is fully dark several minutes later. Having two doors allows everybody to go in when they want without worries. It makes it a lot easier on me too since if the ducks went in before the geese I would have a fracas to deal with (the ducks ALWAYS went into the small house and the geese would chase them out). It only took two days after the change for them to get the point and now everyone waddles to the correct door/house.
This is the front of our duck/goose housing ......
As to everything else....I can still reach in and get the goose's egg without being attacked. The gander doesn't do more than hiss when anyone gets too close to him or his special lady. He still polices the pond area: No rough duck mating, rooster fighting, or hawk intrusions are allowed on his watch. If he sees any nonsense going on he raises his wings and runs toward the disturbance while honking his head off.
All though I have never owned any other geese for comparison...I would say my Pom's are pretty easy going. My whole family loves them.
However, I would assume they are like any other fowl or animal for that matter: Each one has it's own personality and may or may not act like the rest of the members of their breed. My aunt had an Embden goose that ran her farm. You would pull into her driveway and see it and three or four big dogs waiting by the house: I guarantee the only one anyone was scared of was that darned goose!
Good luck with whatever geese you end up getting!