Dick,
This subject has been discussed several times on this forum, and you can find those threads with the search feature.
I installed a Comfort Hot unit in my 2000 Marquis about 6 years ago an it has worked flawlessly. As a fulltimer who spends almost all of my time on full-hookups, it has been a great addition to my coach. However, if you use your coach for summer vacation trips of 3 or 4 months and rarely spend extended periods of time in the coach in cold weather, it would be very difficult if not impossible to justify the cost of a Comfort Hot unit. The early Patriots with a Hurricane did not have electric water heaters, so a Comfort Hot in those coaches was almost a necessity, but since you have an electric water heater, you will have to decide the question for yourself. But remember, a Comfort Hot system will not replace the performance of a Hurricane, it will just add an electrical supplement to it.
As for the performance of a Comfort Hot unit, you can heat the coach on 30A service when the outside temperature is in the low 40s. On 50A service you can heat the coach with the outside temperature into the mid 20s or a little lower depending on how warm you want to keep the coach. When the temperatures are lower you will have to run the Hurricane to supplement the Comfort Hot system, or at any time that you need to cut back on electricity usage especially when on 30A service because the Comfort Hot unit has two elements that each draw 17A. So on 30A service, with just one element running, there is only about 10A left for everything else in the coach when you figure in the current that the heat exchanger fans use while being powered through the inverter.
Gerald