That's a 34% grade hill..... like I said I think there is a steepness at which the bike becomes a liability, and I do think it is before you hit the 30's .... I'd say in when a hill hits the high teens a runner might begin to have the advantage. I also think the distance you are talking about makes a difference. Have you ever seen the rabid fans that run along side the riders on mountain climbs. They can usually run faster than the racers *but* for a short time only.

Bicycling Science (a neat geeky book) goes into great detail and appears to come to the conclusion that equilibrium is reached at around an 18% grade (but also assumes you are pushing the bike)