I have owned factory Rem 700 Police triggers which were tuned by ATRS and Jewel triggers. The tuned trigger was great, and I don't think going to a Jewel helped me shoot any better - it might make a difference with someone more skilled than myself, but for the average joe wannabe I doubt it.
Is the Jewel nicer, yes, but you really only notice it when it is set way down in pull weight, and the gains per dollar are really starting to shrink. The Jewel comes with two springs for diferent weight ranges, one in lbs and one in ounces - I have the heavier lb range screw installed but set at its lowest weight; I generally want triggers as light as posible, but I would not want to go to the lighter spring.
I have heard that Jewel triggers are safe in that despite being set to almost no pull weight you won't get an accidental discharge if the rifle were ever dropped on its but. I find that difficult to believe, and don't really want to test it out with my expensive rifle, but if anyone else has any information on this I would love to hear it.