lol 220v is more efficient, you're just converting your 110v back to a 220v anyways you lose efficiency in the conversion. The motor runs overall stronger. The less amp draw down the wire means the current draw is more efficient. It might be a small amount but overall 220v is always better.
as mas985 already commented, this is simply not true. The only way you could even 'remotely' try to make your argument would be if you were going to claim that 110v would create more 'voltage drop' because of the larger sized wire being necessary...but even then you would have to prove that the installer was using undersized wire for the wire run that they were using. In my case, the wire run is about 2ft to the timer and another 4ft to the pump, AND my wire gauge would probably be oversized using a #10 wire for that distance and amperage...so even trying to make that argument would be moot.