i think nips are harmless... depending - if the bunny nips you in anger or fright, and you did something you shouldn't have (snuck up, made a lot of noise, etc) then you don't punish the bunny, just leave him alone. Charlie only nipped me once in anger after he got in trouble for digging up the carpet when he was younger - i used that same breeder's trick (ps- it works on cats too) and he hasn't "talked back" when he's gotten in trouble since,
if he nips me now, it's play - if he's darting back and forth across the couch and he gets tired of running across my lap, he will try to squeeze behind my back, if i don't move then he nips me - as before, it doesn't hurt and it is kind of funny. it's enough to get your attention.
i've seen him do the same to Daisy (and vice versa) - and they are just playing. the whole dominance thing goes back and forth from day to day between which is dominant - they're like brother and sister, the bossy older brother and the spoiled little sister. he'll get in trouble faster for beating up on her because is bigger, just the same as i'll let her beat up on him a little bit longer since she isn't even half his size. they don't hurt each though
on the other hand - i had a rex bunny (named Rex) for a few months that i got from a friend's uncle who was a breeder. gorgeous black velvet, but he did more than nip. in the end i had to give him back because on one occasion he drew blood biting Charlie and from me as well when i attempted to pull him off Charlie - that hurt me, i could only imagine what it felt like for Charlie