All this, despite Murray having an "inferior" 2 handed backhand and playing with a wrong sized racquet?
Nobody ever claimed that you can't be more consistent with a 2HBH and/or a bigger racquet. You just need less skill to do so than with a 1HBH and/or smaller racquet. However, for more ultimate power, a 1HBH is better. And for ultimate precision when going for winners, a smaller racquet is better. However, if you just want to keep the ball in play forever, a 2HBH and bigger racquet are better. That's why they are the weapons of choice for pushers.