I'm interested to hear what Jayco tells you, and hopefully it's the same thing we got through the dealer. We get the creaking and groaning too, but IIRC it doesn't matter whether the slides are opened or closed.
The problem we had was with the Schwintec on the big (kitchen) slide. The BR, also Schwintec, hasn't had any issues, nor has the curb side slide with the under-mount motor.
Rob & Kelly, Bella & Brady (Miniature Schnauzers)
2016 Eagle 323LKTS
2016 Ram 2500 6.7L CTD
2015 White Hawk 29REKS Summit Edition (Traded)