RE: Started the building phase and have ?
Hideho,
I'll take a wee stab at this...while I have a 3 inch alum arm on my rudder servo, (pull-pull in fuse) I've used the heavy duty karbonite arms for over 200 flights on my WHEdge without any problems whatsoever.
I'm not an IMAC flier, just all out 3D....I haven't noticed any slop or non-repeatability in my servo function.
Hitec 5945's in the wings and elevators.
Just my experience.