Hello; I have built and flown 3 Mid-stars, wonderful planes. I prefer their flying abilities to the four star series. Mine had an OS 40FP, a Saito 45 then a Saito 50 in the last one, it now has an Enya 46 4stroke in it. the Mid star 40 is a very versatile plane, no surprises, but it will knife edge with the best. I prefer tail draggers, and built them all that way. If you can handle the 4 star, you won't have any problems with the mid-star.