I swap back and forth between my F10 M5 and my wife's 740i and the swap is not as painful as you might think. I'm highly impressed with the 740i and think it's more than adequate in performance and quite punchy in Sport mode.
2013 Silverstone///M5/Executive Package/B&O/20" Wheels/DCT/Black Interior
2012 Black Sapphire 740i/ M-Sport/Black Interior
2013 Imperial Blue///M5/Executive Package/20" Wheels/DCT/Sakhir Orange Interior
2012 Mineral White///M3 Coupe/Competition Package/DCT/Fox Red Interior
2008 Titanium Silver 650i Coupe/Sports Package/Nav/Logic 7/HUD/Black Interior
2006 Stratus Gray 650i Coupe/Sports Package/Nav/Logic 7/Cream Interior