I am not a high rise city type, but I am sure that if I lived or worked right next to a 300 foot vertical cliff of a place, where the way down would likely be clogged, I would certainly have a parachute and a ball peen hammer stashed away. Do many people do that? I think it would be cheap insurance, maybe people don't discuss it much?
Having that level of safety factor might make one sound like a paranoid, but a few hundred bucks in a chute doesn't seem overly imprudent to me. Especially if you are over 30 stories or so. A little bundle stashed away wouldn't be obtrusive.
It might be a hoot at the annual Christmas office party, too.
I would suggest a small cargo chute, as steering won't be happening in that short of a base jump unless you are an expert. The smaller chutes would help avoid any updraft from fires below, too.