We've had two RK models over the past 14-15 years and only once did we have any broken dishes. That was a BAD section of road! We also lost part of the window housing in the bedroom (front) and had a flat tire on that same section of gravel road, so I don't blame the broken dishes on having a rear kitchen. Neither had shocks on the suspension -- an older Jayco and our current (2006) Puma.
We hope to get a bigger 5th wheel in the coming years, and we'd get it with a mid kitchen simply because on the larger ones we like the rear living room. On a small one, we'd stick with the rear kitchen.