I have one that I bought used. The previous owner said it is assembled stock. I'm using a OS91 now but I have an old YS91 that I may try on it. I replaced the stock landing gear with aluminum gear mounted just in front of the wing to make it more stable on the ground. It flies great and I love it. It flies slow, making it easy to stay ahead of, but it is capable of some nice aerobatics (although with considerable "coupling" which is probably mostly due to the wing dihedral). I have flown knife edge laps around our field with it. It flies upside down with zero down elevator to hold the nose up.

I wonder how it would fly with no dihedral? Could be a real blast.