I no longer secure mine at the top center. A) it's hard to reach with my 4' ladder, and B) when I attached it to the rubber seal last time, I noticed it was starting to pull the seal off the Roo.
I suppose if I end up in some high winds, I'll try a little harder, but so far they stay in place fine. I do double-up the clips at the top corner on both sides to help keep it in place.
On other tipe...get carbiners and you can connect the shock cords easily and quickly. Pic here: