I did the same trade up last about this time last year and the dealer, Pontiac RV in Illinois, did not dewinterize for the PDI, I didn't ask them to and was glad it was set up for winter. I didn't try the water pump or heater until our first shake down in April. Everything worked perfect. Make sure your tech shows you the valve positions for the heater bypass. I've had good luck with my FR3 and the dealer handled my issues (door closer & camera) great, so don't despair.
2015 FR3 30DS
Towing 2016 Chevy Sonic LT