I built my own 60W one last year for $10, and a storm rolled in on Halloween night bringing both rain and wind. The webs stay put GREAT. Though, standard glue sticks do yellow in the sun.
I'ld build a much bigger one now, and plan to next year, even.
These are the morning after the wind and rain...
This bunch blew all over and got tangled up in the grapes behind. (previously down to the ground) Actually looks better...
Previous to this, we had a display out front for 10 days that had a lot of webs. At around a week in, they had started to show some real weathering. It mostly just added to the effect, however.
In fact, I still have a gob of webs up in a tree, all yellowed, and tangled in with the leaves that fell and stuck in it, that I'm just leaving.
It DOES NOT like to come off of fences, siding, etc that you might get it on without getting up close and scrubbing/scraping it off, however.
If you're able, I'ld suggest building one yourself. If you're wary of that, there's several options on the market for fairly reasonable prices (compared to just the equivalent glue gun). You'll never go back to the stretchy bag stuff again, that's for sure.
The bigger the gun, the faster it'll spray webs. And, adjustable airflow at the gun is VERY handy. If you're buying/building, keep those things in mind.