My setup is 3S, but I prefer a 2S. I cant get properly balanced plane with my 2S packs (350mah 2S). I get perfect Cg with my TP 480 3S packs. I do have a question, does your MXS-C couple in knife edge? Mine does, I guess I will check lateral balance. I know with the Laser, it was very forgiving with respect to the setup. No coupling and everything just flys perfect.
I am still chasing the setup on the MXS-C. I check CG at 3.5" and it seems perfect, I get level flight on 1 click of up elevator at 1/2 power. But when I roll inverted, the plane climbs like a bat out of hell, which means tail heavy. I am sure this is why the plan tucks to the gear in knife edge. I will figure it out, but this thing is super fun.
As far as the build, the only thing I question is the thin piece of pine as the main spar. I know they did that in the Slick-O, but I would of expected Carbon with stiffeners like the Laser.
I look forward to your setup images, and I look forward to flying 1/2 as good as you in a another 2.5 years (that when I will have 3 years in