I've never had an issue with stock servos. The rear has been known to crack occasionally. But unless you run LBA valve body it's only used in reverse, no extra load there. Foot braking over 800 hp the front planet splines may strip. Hurt 1 planet that was in a used race trans before I put 250 passes on it. Haven't hurt one since. Never has an issue with stock pump gears either. Current trans is on year 6, 550 passes. The billet steel drum is very heavy, nearly 10lbs. Better clutch and band life with the A&A aluminum drum. Band strut can be reinforced with a welded brace or you can spend $ on a zoomy piece. I feel the Red lined band works best. Do NOT use a Kevlar band on a aluminum drum. The stock rear band works fine. Most often I'll use the used piece if it looks good. Aluminum goodies, torinngtons, and lightened sun shell wI'll enhance performace, slightly. But longevtivity isn't changed.
Doug