We have them for two reasons.
First, we camp under trees a lot and it keeps all the needles and debris out of the seals.
Secondly, they're a big help with heat coming through the roof of the S/O.
I suspect the problems with sagging in rain is the result of the super cheapo units some factory units get (like Northwood). These are units that aren't even available for sale to the general public. Only a manufacturer can buy this lousy of a product. I am certain I will have to replace them some day.
I installed the cheapest Carefree on our last RV and never had any sagging issues even during torrential rains.
After having it both ways, I would absolutely install them again.
A suggestion; Install the awnings so they have the most possible pitch.