I love my electric awning. It allows me to roll it in quickly if it's going to be windy, or at night when I'm going to sleep. The last time I left a manual awning out overnight, a sudden storm removed it from the camper.
If your awning isn't taut, it probably does need professional adjustment. After that, it'll probably do exactly what it is supposed to do.
As for dumping water, make sure the lock knobs on the arms are loose. The struts can't do their work if the arms are locked. If you want to manually control what side it dumps from, you can pull one arm down shorter, then lock the knob on that side.