I own the one in the OP's link. I bought it because I thought I'd end up with a variety of different handguns and the "universal" nature (and $60 price tag) appealed to me. In actuality I've only used this on Glocks and now wish I'd have just bought one of the more expensive dedicated Glock sight pushers. The tool being discussed in this thread is well made, but I've run into some issues with the design...
- You need to wrap leather or cardboard around the slide when you clamp down on it to avoid marring the finish. As per the instructions, be careful not to clamp down too tight or you can bend the slide in, ruining your firearm.
- You need to use a few coins to raise the slide in the clamp so the "pusher" contacts the sight at the correct height. This is tedious and fiddly.
- You need to add another small piece of leather/padding between the pusher "pin" and the sight or you will marr the finish on the sight
- When you begin to apply pressure to the sight to drift it in, it will try and torque the slide up and out of the clamp. This may require you to reseat the slide in the clamp and reset everything (and you might have to do that more than once depending on how tight the slide-to-sight fit is)
- The pusher really only works in one direction, so if you drift too far you'll need to unclamp the slide (leather, coins, etc) and reverse the whole setup
In short, it works well enough that I'll continue using it (swapping sights on yet another Glock tonight actually). If you use the leather to protect the finish of your firearm it's capable of a professional job (ie you can install the sight correctly without any marks in the finish to show for it)... but it's harder than it needs to be and can be a bit of a PITA.
If you suspect you're going to do this any more than once or twice on a specific make of firearm, I suggest buying a dedicated sight pusher for that brand of gun. In retrospect, that's what I wish I'd have done.