Sorry, I can't give you a better answer than: It Depends...
It depends on the mares, some will flirt horribly with geldings and many geldings will ablige; other mares will just welcome the gelding to the herd, no problem.
It depends on the geldings, some are just one of the herd and blend in, others do try to mount mares. [i've had both kinds. My half-Arab gelding was just part of the herd, and no problem. My husband's saddle gelding is always after my APHA mare (my AQHA gelding is just part of the group, he hangs with his half-sister, or plays with the big gelding). With the minis, one gelding is just part of the herd when he runs iwth the mares; the other was only gelded a year ago, and still somewhat thinks he's a stallion. Both boys share a paddock separate from the mares just to be safe, they get along with each just fine.]