I have the slidefire stock for my AR. I've never installed it given that I've only had it for about 2 months (I bought it used at a pawn shop) I don't personally care to ramble through a bunch of ammo given pricing and availability at this time. But being I got a decent deal on it used, I figure it's heading to the ban list soon so it was more of an investment than anything else. And as for the .22, yes it will work. They have video's on slidefire's site showing it used on a S&W MP15-22.
As for the media knowing about it, I don't see how they couldn't. The thing has been on American Guns, it's all over youtube, and on the website it has a copy of the letter from BATFE saying it is legit.