Arno
Hi, I'm just about to build one myself (OZ version) and took very close note of your comments. From my experiences with two ARF's of late, "Scanner" " Air Speed 40" the recommended CG is back about an inch (2-2.5cm) of where it should be for (my opinion) of nice flying/landing qualities. Subsequently i was landing long, at Mach 2, in a sweat, and making battery, receiver, engine mounting forwards adjustments very quickly. The Scanner required lead!!
The book says 5-6cm at the wing tip. I can't vouch for your calculations but sounds logical. I will start mine at about 2.5-4cm at the tip and go from thier. Interested in how you go with it.
Luck to you
DLA