I had 2 bikes w/ v brakes and susp. forks hanging upside down for a few years, no trouble with the forks.
Added a 3rd bike this year, but there was no extra room on the ceiling. So, I re-arranged some hooks and I have 2 mtbs (heavy low end mtbs) each hanging from the front wheel, and my roadie hanging from the rear. I staggered front/rear so I could hang them closer together. No troubles so far.
They are simply rubber coated hooks screwed into a ceiling stud, so they swing around a bit if disturbed. That's my only complaint. There will be a better solution when we buy a house, but for my situation now it works. They are hanging in front of a window in the garage, so the wall mounted tire hook wasn't an option.