Those kits work pretty good, and just about any competent gunsmith should be able to put a sweet trigger on one. The factory triggers can be worked down to a little under a pound and still be safe. I wouldn't try it at home without one of those kits, but if you have someone with the right tools and know how handy, it can be done for about the same cost and the result is a much better.
Yodave is the way to go. I got two perfect triggers out of one kit. Brooks has a reputation for ripping people off over on RFC. The Yodave is the same thing, but you'll actually get it.
My huntin' pals and I did three 452's with the Brooks trigger kit. Mine turned out right at 2-1/2# and breaks like glass! We paid about $10 bucks each for them but I don't think Brooks is around anymore? Does anyone know if someone else took this over?