I replaced my entire trigger group with a Geiselle group from Brownell's. I don't think that's what you want to know though.... it was pricey, but worth every penny.

Edit: see the thread titled "Triggers" from a week or so ago.

Regarding having someone else do your trigger work... I had Bill Springfield in Colorado, smooth and lighten two trigger groups for me. (Mr. Springfield is pretty well known over on ar15.com, etc.) When I first put them in, they felt very, very nice. When I shot them, they felt very, very nice also... until they doubled. Both of them did. The first one on an older A2 happened when a friend of mine was shooting it and I saw it happen, and the second one (my S&W Sport) doubled on me after shooting about 300 rounds through it with the re-worked trigger. I promptly pulled them both out and replaced the entire trigger group(s) with the Geiselle triggers. Beautiful things, but as I said - pricey. I won't say anything about Mr. Springfield's work - I may have had him lighten them too much for my particular rifles or whatever. Mr. Springfield was great to deal with and had I called him, I'm sure he would have made the situation right... but I didn't trust the rifles, so I went the route I did.