Thanks for the info so far. Bruce88123, that was my next question. Here's where I'm going to need servos:

Throttle
Right Flap
Left Flap
Airleron
Retracts
Elevator
Rudder/Tailwheel

I have four S3151 digitals, and I guess I'll purchase 3 S3004's. Where should I use the S3004's?

Also, I just want to make sure that I'll still have the same benefits of PCM, even though I'm mixing the s3004's with the s3151's.

Thanks,
Joe