RE: magix extra or twist 3d?
I have A ME with an OS50 and the 12.25*3.75. The CG has to be moved back to fly right and keep in mind this is a fun fly plane that is well over powered so watch the speed. And yes the covering is the worst I have ever seen. May be able to seal it at the edges with some type of paint /sealer that would be so nice but do it first before you ever start it.
John