I have the new air foiled tail on my plane. I have no experience with the flat tail version but this one fly's like its on rails. No significant pitch roll coupling at all and very responsive to inputs on the elevators. The only thing I would warn against is that you use the lightest sheeting you can find in the kit for the tail if you are building this setup. I built my tail without the hard wood spars but used stranded packing tape to strengthen the hard balsa used in place. Plenty of strength for that small area!

I hear that the flat tail version fly's as well, however I wonder if it is a responsive to elevator control. The fin and rudder is flat on both version. Have fun!