Wazzbat,

I would offer the advise to get the 7C package with the S3004 servos. These are ideal for planes up to 60 size.
Besides,  I  never strip servos out of  a plane to fit into a new plane. If I buy a new plane I buy servo's suitable for that plane.
Your trainer is ne plane you will probably have around for a while after you've solo'd. I keep mine around because after I pass my instructors test I Will need a complete plane to teach people on.

Once you are ready to move on, then buy the electronics pack from Tower for your next project. This includes reciever, battery pack, servos and switch.
Also if I sell a plne, I sell them with Servo's, Makes it more attractive for a potential buyer since they can always buy their own ARF can;t they. I sell my planes as Ready to Fly