In peaceful mode you get 75% of the EXP you should. In battle you get 100%. You don't get half off, just 25%. Also, with this quest thing, after PKers have done it, they'd still PK anyway so it wouldn't do much but make the PKer stronger after he has finished it. Also if people don't want to go on the quest with the PKer, he will just PK in a mad rage...
