RE: Zen 50 engine mounting distance...
Maybe only my opinion here based on owning 18 or so planes but you are only talking about a 1/16" of an inch difference! Some flyers go for neautral nose up/down for balance while some like me want the nose to dip down about 1 1/2" from level. Some just want the nose to dip down 1/2" from level. Being that there are these differences in how a flyer balances his/her plane I really don't see that a 1/16" is enough to worry about on a plane like the Zen50. Also the Zen50 has a long fuselage and won't be as critical to cg as on shorter types. [8D]