I had three Carefree slideout awnings installed on my 33RLDS and paid $1600 out the door. I can't imagine any trailer without one. As mentioned, they protect the slideout roof and gaskets from premature wear. They do however hold water when it rains, but it all runs off when the slideout is brought in.
2014 Jayco Jay Flight 33RLDS travel trailer, 2005 Chevy 2500 Duramax diesel with 60 gallon auxilary bed mounted fuel tank, Honda EU3000 generator.