I would run as short a servo extension as you can get away with. I have had servo problems related to extensions in the past. I am not sure if length was a big contributor to those problems, but it's possible. Just be sure to not make them so short they can pull apart.

You might also consider going to a 5 cell, 6 volt pack. You get more power and faster transit times from the same servos. I am doing this on most of my fun-fly planes now and it seems to work really well.

I agree you will love this airplane, especially with a 9C. One thing that's really cool about that radio: you can have a setup you like, then copy it to a different memory location. Then you can experiment and still have your original setup to easily get back to if you mess something up. I have had literally dozens of hours of fun setting up different mixes!!!

Enjoy...