Yes, it does stay on when my cock is soft.
Although once, during initial experiments in my apartment, I was on the computer for a while and my dick went down to a TOTAL softy, and it was kind of easy to pull it off my cock then.
When I'm walking around a store or something, I touch my dick now and then and kind of rub the coronal ridge a little. Gives it a tingle that can be felt right through the rubber and helps me maintain kind of a semi hard state. Not hard enough to make it poke out, but stiff enough not to let it get totally soft either.
There are local community events both this weekend and next weekend, I'll be walking around both with my big schlong slapping all over under my loose fitting shorts! Fun time!
I'll report on any particularly good incidients that may occur.