David:
Kahr's web site has some pretty good info about their models. They seem to be selling three K9 models right now, black, stainless, and stainless elite.
The web site gives a good description of the Elite trigger: "The trigger stroke has been reduced to 3/8" from 1/2" to provide faster firing. The shorter trigger also makes it faster to fire in critical defensive situations."
The only other differences are cosmetic. However, by the time you buy a Kahr K9 stainless, send it back to Kahr to be upgraded to the Elite trigger, pay for shipping etc., I suspect you'll probably have spent as much as it would cost to have purchased the K9 Stainless Elite in the first place. Unless you get the black model and install the trigger yourself, I don't think it would be worth it.
Jared