Just remember also that the airplane in question, whether EAB or Standard or any other category, must have ALWAYS met 100% of the criteria, since day 1. If (for example) your Champ had an STC that bumped its max gross weight to, say, 1350#, and you remove that STC and return it to a lower, LSA compliant gross weight, well, tough. Still not legal for a Sport Pilot to fly. Ever.
Arenít FAA regulations fun?
But this has not much to do with an RV12. Those can be flown by anyone with a Sport Pilot or higher certificate, assuming you havenít had a medical revoked.
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)