Those are good questions, and I won't try to answer Powerchip's part for them - but I can ask them and pass along the info.
As far as the other company you named:
Dinan: He doesn't get official help from BMW on this, unofficial maybe. He figured it out though.
AA: They have not really been first in developing software for any of the new models. Not a slam on them, it is just not their primary focus.
Technik: As you claim for Powerchips, they don't specialize in BMW either.
Conforti: As far as I know he is not aggressively pursuing this right now.
I don't think it is a huge stretch of the imagination to think that Powerchips was able to develop their own software that produces significant performance gains. Customers dyno test their cars all the time to back up any company's claims. How long do you think they would be in business if it got out that they were fidging numbers (or fudging them more than everybody else at least)?