As Shakespeare would say: "Aye, there's the rub!" This kit is definitely still at the prototype stage. I'm only aware of one other CDScaleDesigns SE5a that has flown (Teus' model) and I don't think more that a dozen were ever sold. The plans show the CG at 12cm back from the leading edge and that's where it was for the maiden flight...which was a disaster as the model was absolutely uncontrollable and I have no idea how I managed to get it back on the ground more or less in one piece.

Using the calculation shown on the RC Groups page above, I came up with the new position of 9cm back from the LE. I then held a dowel spanwise at that location (to avoid the influence of my fingertips) and added weight to the dummy radiator. See the first of the balance photos above. Technically this is slightly "nose down" since with the fuselage center line would be perpendicular to the TE of the rudder (and the stab is actually a +3 relative to the centerline).