Lowering average level of your group will increase xp gains tremendously. If you found 2 random lowbies you could boost, your RAF toons should get around 50% more XP each kill. It will increase eve more if you can boost with a lower lvl character.

Its been a while since I boosted now, its strange that your toons get no xp at all. It almost sounds like instance boosting was hotfixed in a way.