I wasn't going to speak to this again, but I've had a lot of issues niggling at me, and they finally coalesced today.
First, the shootout wasn't science. Now, before anyone goes all crazy over this statement, hear me out.
Science is a methodology in which you first form a hypothesis, then collect data in an effort to disprove it. If you can't, then the hypothesis MAY be correct, at least until more data comes along. You can't PROVE anything, except perhaps in mathematics.
No, the shootout was pure and simple data collection, and from a limited sample size of 1 for each of the transmitters. That was freely admitted.
It's quite possible, and in fact, highly likely, that the results for the AMT5000 were compromised. Because it would have been my hypothesis that the Rangemaster and the AMT5000 would be relatively similar in results, and lead the pack in terms of efficiency in delivering a signal to a Part 15 antenna (I'm not familiar with the Grain transmitter).
The fact that the AMT5000 performed relatively poorly could be from a number of factors, particularly since it's constructed from a kit, where quality control of the final product is unknown, and any number of things could happen to individual parts during the assembly process. I've owned 4 factory assembled ProCasters, and their individual performances (in the same installation) have even varied widely.
But instead of attempting to determine the reasons why, the single sample data has been published on the Internet and a magazine. No one is likely to read the caveats associated with it - they'll just take away the results (I'd be surprised if even 10% read the methodology used).
So while the limited data available is interesting, and a start, it's hardly the final word. And hardly science.