My main toon is consistently higher on the aggro list by default unless something interrupts mind flay. he's also consistently higher on the damage meters as well, primarily due to the fact that when the mob dies, his mind blast almost always lands, where the other 3 might not register as the mob dies a split second before their spells go off. Likewise, my main's DoTs will almost always get the maximum tics where the others might have one tic left when the mob dies.

Not always, but enough to show up on measurement tools.