Yes, the studies on using EM in poultry generally do show overall increased production and health. I'm not that methodical about it so I can't claim such results. I also started them on EM almost the day we got our first (full grown) chickens so I have little to compare with. When I first read about EM, there was something about it that just rang a big "do it!" bell inside me. The more and more I learn about gut/digestive health, the more I am convinced that it is a key to overall vitality and health of any living creature. I don't like pills, whether probiotic or antibiotic pills and prefer to get my "medicine" through food. We ferment or soak a lot of our foods for maximum digestibility and thus EM just seems a natural continuum of it.
I haven't experimented a whole lot with different types of fermented feed, but I am preferring the results I get from using EM to ferment the feed. I have done some feed without any starter and am not as happy with the results. There are folks who will think it is overally complicated to use a starter, and I will agree you don't need it, but I think I get a better ferment from using EM as a starter.
We've never done CX so I can't comment on their smell. But since using EM to spray down their housing 1-2x/month in the spring/summer/fall and using EM fermented feed, I do notice much less smell with our 9 large fowl and 3 silkies. They free range in the summer so there is naturally less poop in the coop/run but in the winter, the EM FF combined with a deep litter method is keeping the smell not non-existant but barely noticable. This spring/summer we plan to raise some Dark Cornish and/or RIRs for meat so it will give a more intensive test of the EM...but then again I have never done this before so I have nothing to compare it with.
As far as this info being out there, it's not new. It started in Japan in the 80's and only about 10-15 years ago did it make it's way to the USA. It's an extra cost and effort, but one I feel completely worthwhile. Some folks are reluctant to change in part because it could take a season or two to learn how to maximize production while learning how to incorporate a new method (such as EM). Some of the claimed benefits of EM are hard to prove as well and some of them start to sound a little too good to be true and/or "woo woo". There are quite a few more scientific tests out there (similar to the links I posted earlier) about EM usage and results.
A tangent to using EM for chickens, but incredibly fascinating...using EM for bioremediation, in this case for the Fukushima fallout:
http://holisticradioprotection.wordpress.com/category/bioremediation/