I installed one on my 300 RUM a couple of months ago. It's pretty much like Al said. Not too difficult if you are mechanically inclined and feel confident taking a file to your safety. If not, a smith could do it for you for a small fee.
I set mine to 2 1/2 pounds, nice and crisp. That simply cannot be accomplished with the factory trigger.
I don't know how these compare with the big name triggers out there since this is the only one I've done but I guess it doesn't matter since they're the only game in town for A-Bolts.
It accomplished what it was supposed to. But I did think the price was a bit high for what you're getting. I guess if you want a good trigger, they have the market cornered for A-Bolts so you don't really have a choice.
In short, if your dad wants a better trigger, the Moyers will make him happy if he doesn't mind the price.