Servos are one of the most important links you have, especially with a precision airplane. Resolution and centering are critical, as is high torque around neutral, so the surface comes back to the same place everytime, under any loading or flight condition.

My rule of thumb when choosing servos in order of preference Lowest to Highest is:

Cored analog >coreless analog>cored digital>coreless digital.

The digital amplifier and it's much faster updating seems to counter the effects of the cored motor to a great extent.
There are some exceptions. My experience with Hitec a cored digital (sample of 1) was not good because of a lack of resolution around neutral. This was even after the deadband had been set to the minumum with the Hitec programmer. I didn't want to spend the money to try another, so my experience may not be typical. In contrast, JR cored digitals are very tight, even some cheap DS537s I got for a small airplane. I've had good luck with Hitec coreless digitals after the deadband was set to minimum. Hitec coreless digitals aren't QUITE as tight as JRs, but they are very good. I don't have direct experience with Futaba digitals, but I know that a lot of people who fly Futaba equipment use JR servos.

You also want a FAST servo so it will follow your movements on the stick very quickly. I always run 5 cell packs or a 6 volt regulated Li Ion pack for that reason. Speed should be .15 sec or less at 6 volts as speced by the manufacturer. 6 volts also has the benefit of giving higher torque and holding power.

You can save a few bucks (and weight) by going to JR DS3421's on dual elevators and JR 9411's on ailerons. You can use the SA versions of these servos (nylon gears) and save a few more bucks. They are very high torque for their size, and are very precise. You can also save a few bucks using the JR 8411 SA on rudder, again with nylon gears. Unless you want to do 3D, you don't really need the metal gears, and the nylon gears are essentially slop free and stay that way.

Bottomline, I think you would be unhappy with that choice of servo in a 2M airplane. Buy the best servos you can possibly afford.

Disclaimer: I am not sponsored by anyone, and have no financial interest in any of the companies discussed above.

Jon Lowe