I've just noticed that if i hit one of my ally's raid bosses, i only get a 1.1x ally bonus even though there are at least 3 of us attacking the boss. (I just saw two of my teammates as MVP and JMVP, didnt look to see if there were more). Isn't it supposed to give 1.x (where x is the number of your allies that participate in the raid?). Perhaps this is a bug?
I have gotten 1.3x and 1.4x bonuses before on raid bosses I summon, so perhaps I am missing something.