Hi there, well iv been keeping a breeding white-lips for about 8 or 9years +- now I think, so I know a fair amount about there care/husbandry.
There is also a really nice article on them at the moment in the new ultimate exotic magazine, which should get you up to speed.
a bite is said to be mild

however I find this statement a bit over an under exaggeration, this is a venomous pit viper after all, and the reason why I think people take the bite so lightly is because I don’t think there is anyone who has actually taken a full on bite from an adult specimen in S.A, well at least I haven’t heard of any, and to ad to that I haven’t heard or read any real facts on the bite from this animal in general, so there aint many people around who can give you a solid answer on that . So PLEASE don’t believe what you here and practice allot of caution when handling your animal, whether it be a black mamba, or a white lip, it doesn’t change the fact that this animals has venom for a reason, to kill and to defend. Id say the bite is naaaassty to say the least! And don’t ever under estimate the power of venom.
BV has a post up at the moment of what a tiny neonate horned adder can do, which is also said to have mild venom, lemme tell you it doesn’t look fun.
Otherwise congrats I have no dought in my mind at all that you will love your white-lips to bits, mine are great!
cheers