Just buy 2 "good" servos and put them on your ailerons, then you will understand. A long time ago I had plain ball bearing servos in my first pattern plane, and I was happy. Then I freind let me borrow 2 coreless servos to try for a weekend. Wow, huge difference. I ordered 4 new coreless servos that night. You will be a better, more precise flyer with good servos. Just try it.