53x11 is advantageous on a long descent or in a TT with downhill portions, it's like a secret weapon that can be used to spin at a self-selected cadence and maintain a consistent power output.

that being said, I simply use a 53x39 and 12x25, I ride crosschained big to big all the time. I have yet to be in a sprint that I was spun out on, but have been overgeared due to operator error on occaision. Only time I wished I had a rear dinner plate bigger than a 25 or an inner chain wheel smaller than a 39 was going up brasstown bald after unicoi and hogpen gap, that thing was too steep for 39x25, at least for me, and I was glad for the pushes I got from the crowd awaiting the T o GA peloton arrival. although I'm sure I looked pathetic.