My roof covers 2,000 square feet with three louvered, screened gable
vents amounting to 9 square feet or 4.5 square feet of free area.

I'd like to add ridge vents. With a pitch of 6 in 12, I want to be able
to throw a rope across the ridge for safety if I work up there in the
future.

Will a rope crush a ridge vent? The metal ridge vents in my
neighborhood look bent.

I see three kinds for sale:

Air Vent Multi-Pitch Filter (aluminum)

Air Vent Shinge Vent II

Dow Corning Vent-Sure Rigid Roll

What's best?