The Jayco website lists the 2013 version not the 2014 version. My 2014 Greyhawk came with a tankless heater. Caveat emptor on the tankless water heaters however, they need very smooth water flow to have consistent temperature. This isn't the case when you are on pump water. You may want to get a 2 gallon accumulator tank just in front of the tank-less water heater to keep the pressure up. The other issue is tankless water heaters work on propane not electric like the tank versions, this means that you can't use the "free" electricity at parks to keep the water hot when not showering. I would only turn on the propane when we shower in the morning (or when dry camping) and then use electric during the day. Many people who have the tank-less version have reverted back to the tank version because they could not deal with the problems from the tankless water heaters.
2004 Chevrolet Silverado 3500 LT with a 2004 Jayco JayFlight 29BHS
2014 Greyhawk 31FS with a 2007 Tahoe toad
2014 Thor Palazzo 33.3 with a 2007 Tahoe toad