ORIGINAL: Not24
I take it the 2300 you had was an Italian one? I have the new one with the carb barrel slot fixed. Mine has no midrange problems. It has an occasional surging in level flight, and goes lean in a right wing high knife edge. Also running F plug and 10% powermaster. Engine has 2/3 of a gal thru it so far.
It will smooth out after about 4 or 5 gallons of fuel.
Maybe drop the nitro to 5%. Not a big deal though. Just don't bump nitro up to 15% or you'll have lots of problems.