Six days before I got married I was sat in a dentists chair being treated by a trainee dentist. I'd managed to break a tooth and the remaining stump had to be removed. After half an hour of pulling on the stump he gave up and let the supervising dentist take over. She had the tooth out within about 10 seconds.
It turns out that removing gears and wheels from an axle is a bit like pulling teeth. Experience and the right tools and it can be a quick and (fairly) painless process. Use the wrong tools and it can be a slow and frustrating process.
When I built the first test chassis for the Hudson-Hunslet diesel I found getting the wheels off the axle exceptionally difficult. It's supposed to be possible using a set of pliers and a hard surface, but that didn't work well for me and in the end I destroyed one insulating plastic part and bent an axle. Now the wheels aren't two expensive (£1.25 per axle) but I wouldn't have to ruin too many before it got costly.
So far I've tested it by removing a wheel from an axle and pulling a worm from a layshaft both of which it did without any effort at all. If you are tempted by one be careful where you shop though. I bought mine from Amazon and paid £11.95 although the price does seem to fluctuate a little. If you look on eBay though they seem to be on sale for around £112! I think someone got the decimal point in the wrong place but amazingly the page suggests that they've sold at least 17 at that price. Some people really do have more money than sense.