I agree with t. caster, what has caliber got to do with it. Plain or pretty, big bore or small, when the gun is done, and your aiming down range, you want a good trigger. You are twice removed from the ball going down range, the lock, and the trigger, with the trigger being the last contact you have, and probably the cause of more misses than any other single factor. I think, every thing else being equal, in man and gun, a set trigger will out shoot a plain trigger almost every time, you can't beat the spontaneity of a spring loaded light trigger. Thats not to say a plain trigger can't be made to shoot well, because it certainly can, it just takes more time at the work bench, and more range time, so you are more in concert with that particular trigger. I hunt with both, but If I plan to hunt with a plain trigger, I do spend more time at the range, until the feel of that trigger becomes so ingrained, I don't have to think about it, I can be more single minded about what I want to hit. I think the Japanese call it "moo-shin", no-mindedness.
My opinion, for what its worth, if you shoot against someone and you have an ounce of competitiveness or hunt and have any sense of responsibility for making a clean kill shot, you would want the best possible trigger you can make for yourself, plain or set, still, things can happen.
Robby