I rolled out two new systems to my users at the end of last week. The new hires picked up everything with little effort, because they were learning something new. The old timers struggled because they have to learn different ways of doing something they already know.
This is where I made my discovery: it is much easier to learn somthing new than something different. It probably has something to do with habit. Once something is ingrained, you have to unlearn before you can learn.