Why do bards earn less exp than non bards?

First noticed this in Karnors castle... I was mentor target had vit bonus, 1 level 90 bonus and 110% potion at level 72, we also had a 69 ranger in the group as well with no 90's 110% potion, had vitality bonus but not mentored to. Over the course of an hour and a half he levelled from 69 to 74, while I the dirge went from 72 to 74.
Last night I played my levell 44 coercer, joined in a group with a friends trouby who was also 44... she has 4 level 90's to my 1, had full vitality, 110% potions and her hubby had her as mentor target... she did have 40% of exp directed to aa, My coercer has 1 level 90 bonus, 110% bonus and full vitality, I was not mentored to and had 50% exp directed to aa... at the end of the run through tower and cazic she was level 47 just dinged and I was 85% to 49.
No where have I read that bard classes get a negative modifier to exp compared to other classes but this was readily apparent after the 2 tests... I just wondered if I missed reading this somewhere or if its just another of sony's unpublished punishments for playing certain classes... like the knight exp thing in eq1 or where haffers levelled faster on eq1

Sorry man but all are equal when it comes to xp and vitality.

The only possible thing I could think of is the one that lands the killing blow could be recieving a small portion more of the xp for being the one that fell the mob, and for the most part, bards don't do alot of the killing in groups like the ones you described.
When leveling my troub (the first one I took through SF) it leveled just as fast as my wizzy, warden, and paladin. Each time I put my aa conversion to reflect the % bonus xp I was gaining from cap level toons (which does not equal out to 10, 20, 30 btw) and they all dinged 90 at about the same place.
So in solo context they absolutely are all equal. Any discrepencies you are seeing in groups may be based on how the division of awarded xp is done.

If everyone isn't exactly the same level its going to change the distribution as well.

i thought u were crazy when i seen this post. so i decided to track my exp gain on my 81 necro and my 81 dirge and my necro gained 21.3% more exp for the same kills/quests my dirge did, so hes not crazy neither toon had anything +VItality