RE: Thoughts on Balsa USA Eindecker 40
It is VERY sport scale. If you just want an easy build and bit of a WWI feel, then it can be lots of fun. If you're looking for a scale model of the Fokker EIII then you may be disappointed. The wing is the standard fat airfoil BUSA design and the "rigging" is definitely just for show.
The most common modifications to the kit seem to be to replace the "slab side" fuse construction with a "stick" style frame and also to replace the push rods on the rudder and elevator with a pull-pull system. On the original EIII both the rudder and elevator were "full-flying" which means there was no fixed fin or stabilizer as on the BUSA Eindecker. So some modelers make this conversion.
Wing warping would only be possible with a wing of scale thickness and flexibility. It would be completely impossible with the BUSA wing type.