If I was late to the point where I might miss a connection, I'd take the conventional route always. Much easier to argue you did what you could to get to the gate on time.

I doubt the difference between walking and riding, probably just a few minutes, would be a major factor in getting boarded. You have to scan a boarding pass at flight connections I think, and if this is within the conformance time, provided you get to the gate promptly I'd imagine you'd be allowed to board as the system would know you were in the terminal (still more if you had checked through luggage). But I'd be interested to hear other peoples' thoughts on this.