High performace D/F is my suggestion --
Unless you can find an AMA / CD / designate that will sign you off doing "the demo" flight with an aircraft of lessor performance, ?? you should look toward mastering a higher performance D/F.
Remember the new rules say the demo flight must be flown at 150mph. The rule is not clear as to how much or how little of that flight can be flown at speeds less than 150. Not many D/F actually will fly at those speeds, (unless going straight down) and none of the Byron types that I know of will.
Nat Lancaster (district IX AVP) and I, submitted a proposal to the safety committee / AMA. That proposal included reducing the "150 mph" so high performance, complex, high aspect ratio, commonly available war birds would fit the ticket. The AMA's answer was a clear NO --- the higher speed is a must !!
If the sign off CD / designate sticks to the "Rules by the book" (hummm how many do??) not many war birds would fit the aircraft criteria. For the most part just the "Madeira type Racing war birds and only the fastest of them" 150 mph is faster than you might think. We in the turbine world are use to the higher speeds, but most R/C model aircraft will not even come close to sustaining that speed.
If you can maintain, sustain, and time after time operate a high performance D/F you can easily and safety transition into a turbine powered Jet. On this point no one would disagree.
Nat's and my argument was that there is another level of complexity, and slightly lower speed aircraft that can ingrain the same learned prerequisites for safe turbine operation. See attached letter of denial, of our proposal from Don Lowe, the AMA safety committee chair person.
Lee H. DeMary
AMA 36099