I got a response from the guy today and I was right, but TC isn't behind it.
A gunsmith in MO. has come up with a breechplug that doesn't use the Hornet or ACP brass just the small rifle primer, the same size as a #11 cap. It still is in the testing stage so he won't go any further than that, but promised to post results comparing the 209 and the new concept plug in the future.
One advantage I can think of right away is the lack of crud ring from triple 7 powder that is reported in the rifles that use #11 caps compared to the 209 primer. I have personal experience with the 209 crud myself!