Nah, with stamina and party bonus u'll gain almost same exp, I was hunting with other guy and we both get a little more than 10k exp for 1dl(with stamina and shared exp) - close to amount that I should get while hunting it alone without stamina bonus.Them hunting in a party would mean the following:
#They receive less exp per monster that they killed on their KILLS STATISTIC (their killstatistic says they killed 100 demons; that would mean 50% less exp if they were with 2 people).
If they did get all that exp from party hunt then their kill statistic should show a MUCH higher number of kills
Also there is exp for chests, tasks so..