Something to consider is carrying capacity, amount of water you carry, your holding tank sizes and the list goes on. We went with a DP for some of those reasons. We carry 100 gallons of fresh water and can get 7 days before needing to dump. We have the inverter/charger so we can dry camp without running the gen set.
The largest gas coach I have seen is 36 feet, with smaller holding tanks.
Do the test drive of both gas and DP and you will see the difference.
Good luck with your choice and welcome to a really great life style.
If you decide on a DP, be sure to check the EPA regulations and the cost of DEF or replacing the exhaust system. Many factors to consider.