I flew the JR Exlporer.
It was a good bit more nose heavy than the Excelleron. Don't ask me how since they are basically the same plane.
I had a YS110 with the tank and battery on the CG. With 4 ounces of lead on the tail under the stab it still felt nose heavy and needed more push inverted than I liked.

Tomorrow I can get you the actual CG recomendation from my instructions . All the setup recomendations are differenet than the Excelleron. Especially control throws. Rudder 20mm Elevator and Aileron 10mm

Eddie