Wade and Lee Ann, I am one who actually went the other way. We towed 4 down for 4 and 1/2 years and went to a 20' enclosed trailer set up with our 40'Dutch Star and doubt that we will ever go back to 4 down.
I am just under 65' and have had zilch problems at campgrounds. I like the idea of being able to load/unload the car with no concern for the weather or time of day as with internal lights I can see and am always dry. The car always arrives in same condition that we load it and we have full time braking with the trailer vs. panic type braking with 4 down. Other than tolls, I have never been charged extra for the trailer and have only needed to unhook once in 2 and 1/2 years using it. I really like being able to back up at will with the trailer which is not going to happen with either a 4 down or a dolly set up.
Tires are the only real maintenance item with the trailer; whereas, with a 4 down in addition to tires you can experience front end issues, etc.
We do not full time; but do travel 8-9 months of the year and manage to put on around 20,000+ miles per year- this tends to happen when you have kids in Boston and Phoenix.
Proceed as you will; but, evaluate all aspects before changing. BTW, your trailer will have virtually nill depreciation; however, tow bars, supplemental brakes, etc. depreciate very quickly, Ken,'04 DSDP....