TechReports overclocking results:
4.8GHz, 1.475V - reboot
4.7GHz, 1.4875V - lock
4.6GHz, 1.525V - errors on multiple threads
4.6GHz, 1.5375V - errors with temps ~55C
4.6GHZ, 1.5375V, Turbo fan - stable with temps ~53.5C, eventually locked
4.6GHZ, 1.5375V, manual fan, 100% duty cycle at 50C - lock
4.6GHZ, 1.55V, manual fan, 100% duty cycle at 50C - crashes, temps ~54.6C
4.4GHz, 1.55V - ok
4.5GHz, 1.55V - ok, ~57C, 305W
4.5GHz, 1.475V - errors
4.5GHz, 1.525V - errors
4.5GHz, 1.5375V - OK, ~56C
"There's a 48W gap between the TDP ratings of the Core i5 parts and the FX-8350, but in our tests, the actual difference at the wall socket between two similarly configured systems under load was over 100W. That gap is large enough to force the potential buyer to think deeply about the class of power supply, case, and CPU cooler he needs for his build. One could definitely get away with less expensive components for a Core i5 system."
Okay, so let's use your figure anyway. So the undervolted 8350 uses 18 watts more than the 3770K and is 25% slower in highly threaded applications. Is that more to your liking?
(We don't even have to talk about lightly threaded applications)