I used a lot of it on my old stick built, I would suggest caution. If you ever have to replace the vents you'll be in for a huge headache, the stuff is very difficult if not impossible to remove. If you do go ahead with it, be sure to prep the area correctly so it adheres like it is supposed to, you don't want to make mistakes. Sure works though.
While in Arches last fall the folks next to us got hammered by hail shattering all the roof plastic, vent domes, fridge vent, and such. S@!% happens.
Might not be a bad idea to try removing some first, stick a square of it to something and give it a shot. Mine was on a rubber roof, using scrapers and such was not an option.