I'm going to give the counterpoint argument.
I purchased a B&J Machine P500 Universal Sight Tool from Brownells about six months ago.
I had planned to use it to install night sights on a H&K USPc and a Kimber 1911.
Despite all my best tightening down and repositioning efforts, the device would not hold the slide of the USP steady, and as a result the pusher rod marred both the side of the sight and the slide. It's hard to see, and I was able to touch it up with a little cold bluing, but it doesn't make me happy.
When I tried to use the sight pusher to remove the sights on the Kimber, both the sight pushing bolt and plastic liner broke.
I've gone back to the vice, brass punch and hammer method.
I cannot recommend the P500 tool.
In comparison do have a Glockmeister sight pusher tool for my Glocks, and it works great. I have a friend who has the super-duper expensive ($600!) Meprolight Universal Sight Installation Tool, and it is a quality piece of machinery that works well also.
- Cioppino