Yes it was me that suggested staged weaning. I still do it on most of my animals. The one exception now is first time mothers (I take the pups ASAP, before they have had a chance to produce much milk). Even when filling orders I wont take all the pups from an experienced mother.
Ive found that the staged weaning will produce healthier and larger rats when compared side by side to ones that are stopped abruptly at 3 - 3.5 weeks. It also gives the female an extra week to recover (producing milk takes alot out of females, it takes vitamins and minerals that the female could use and gives them to the baby, it also reduces fat stores.)
Rats are referred to as weanlings at 3 weeks ... however the female wont usually start kicking them off until 4 weeks.
If you are going to remove the female its best to do it before they drop their litters. Doing so afterwords will sometimes make the females "freak out". Theyll grab one of the babies and run back and forth across the enclosure trying to stuff it into every nook and cranny. This has even happened on litters over a week old. Its stressful on the mother and can be fatal to the pups.
If you get a full fledged bite (one that draws blood) you need to get rid of that rat ... this seems to be a genetic disorder and will get passed along. Nips are fairly common ... just make you jump a bit. Although it is suggested that you use gloves when working with rats you can tell alot more about them by getting "hands on".
Bryan