Difference between 10 and 11?

[warcraftisgood]

It's 30%. If your 10-segment experience bar has less than 3 segments filled, then you are still considered to be 1 level lower to mobs and bosses* and their level is adjusted accordingly. This is true at any level (a reason why FTP's may still want to turn off experience on their 20's which precludes them from RBG's).

*dungeon bosses and mobs will not be adjusted lower than the minimum level requirement of the dungeon or area

nay it's 25%. i had to rebuild my og 11 since i was at 29% and after some advice from dpook, tested it personally and mobs are scaled up.