In the earlier runs these things would hit around 3.6Ghz on air. But nowadays the E4XXX, and even E6XXX's are lucky to break 3.0Ghz. Some wont even get to 3ghz. They max out at 2.8-2.9Ghz. Intel quit building the "overkill" into the C2D months ago. They still OC well. Just not "stellar" like they used to.
I only mention this because alot of people new to C2D dont know this. Try to find a early manufaturing week of the E4XXX and your good to go. Like week 30 or earlier.
I have quite the opposite experience. I bought my first C2D E6400 in October or November. It needed 1.48v to be stable at 3.2GHz. The last week I replaced it with E6420 and I was surprised of its OC-ing abilities. It runs stable OC-ed to 3.2GHz, but undervolted from 1.325v to 1.28125v. Two months ago my friend bought an E4300 and it runs stable OC-ed to 3150(9x350) @ 1.4v. So I guess it is more a question of luck.
The allendale core originally used the exact same "recipe" as the Conroe core which allowed them to clock nearly the same but Intel quickly changed the "recipe." Now Allendales are largely limited by the core, not by other components. My E4300 went up to 375 @ 1.55vcore with temps @50c but I couldn't really get past it. With a full week of tweaking I could get ~385 most likely but I have run into a core limitation. Conroe's easily surpass the Allendale counterparts in OC'ing ability but they cost more (obviously).
Since all 4 series are Allendale native cores I expect the 4400 to scale nearly identically to the 4300. ~2.8Ghz on stock voltage and then the requirements quickly ramp after that.
There is an entire thread devoted to the 4300 clocking
here