I'm learning frostfire mage. Cloak of Fallen Cardinal dropped in non-heroic POS. Holy pally and I rolled *need*. I won, he told me mages don't use MP5, and for me to give it to him. I minimized my screen to try and research it real fast to see if mages don't benefit from MP5. I couldn't find anything in time. When I returned to game, he he left the group but not before saying he reported me.
Even if he reports you, as long as the item is an upgrade for you, you won't get banned. You benefit from mp5 as well, mana user after all, it's just not that good of a stat for you. Don't worry.
I eventually found an article in the wowhead wotlk section where the author said that mp5 is generally more beneficial to healers than to dps. So believe it or not, I found the holy paladin in Dalaran and offered to give it to her, but she had me on ignore. I even turned around and equipped and unequipped it for her to see, and tried emotes to get her attention. I eventually gave up.
My post here wasn't really to address a concern that I have that I would get banned, because I don't have concerns that I will. It's more to validate what she told me about mp5. Again, I'm learning the class and I just want to learn from my mistakes. My attempt to give the item to her was an effort to do the right thing, based on what I read at wotlk wowhead.
In general any self-respecting hpal shouldn't roll on crit/mp5 items like that cloak to begin with. But sometimes you just gotta make due with what you get - same is true for both of you though, so it's totally fine for either of you to roll need on it.