ive had both. In my experience, theres little reason for a slide awning unless the slide has a raised outboard lip that would make you sweep out leaves or snow to close it. Even then, debris will find a way to get under causing you cleaning issues and water infiltration concerns.
No reason if your slide does not have a raised lip as closing it will sweep off all the debris and snow.
Theres some $ pennies advantage for shade during cooling season, then theres the noise of it flapping on windy days or nights. Money poorly spent.
Its a looks great salesmans pitch. use your money better.
max. 42 years no longer a camp owner