The level disparity is always going to be a big factor and bigger factor with a hybrid higher level. As you stated - the name of the game is just staying around people your level. The hybrid in a full group becomes alot less of an issue because while you will gain less of the available XP by quite alot sometimes, you still take the same amount of mobs to ding due to the fact they need more mobs to ding, they get more of the pie (which I am sure why this system exists in theory)
It only gets noticably unfair when you have something like example below - a hybrid who is higher than another hybrid in group. The lower hybrid (paladin in this example) not only gets alot less of a XP share, and the fact that he is not just 1 level lower but SEVERAL levels lower than the highest hybrid, he gets jobbed pretty hard:
[You must be logged in to view images. Log in or Register.]