Mark,
The Canadian summary sheet (link above) makes it pretty clear (it’s even underlined) in the “Questions and Answers” section…
Last sentence of #2. “For Micro and Mini, if you upgrade your old engine to EVO, you must use a cylinder marked with a lettered production”.
Given that US and Canada specs appear to be the same, I’d say it’s pretty clear what the intent is.
At official RMax events, the kids have to run the newer cylinders, if they want to run EVO kits.