I agree, a HWH by-pass is a nice feature and comes in handy...., especially should you have to address an issue with the HWH while camping and maintaining water supply.
Just a FYI........:
2006 Jayco PUP Owners manual winterizing procedure w/o by-pass (p. 96 & 97):
2014 Jayco PUP Owners manual winterizing procedure w/By-pass (p. 8-5):
In the 2014 Jayco owners manual, note the Jayco recommendation in respect to RV antifreeze and the associated HWH.