@footie: Would this be the first time a thread wandered in it's discussion?
Also haven't the actual test numbers and opinions/analysis posted herein fully answered the original question?
@gbb: I really don't think I owe you any reply nor help in understanding the performance of cars based on your poor attitude and insults but here are some big tips. Power and torque are second in line to torque delivered to the wheels (across a broad rpm range) divided by vehicle weight. All of your other "points" are fairly inconsequential without looking at this level of detail. Which brings me to Bruce....
@Bruce: After some further thought, investigation, simulations and your posts as well
I think the largest advantage of the M3 engine over the LS3 Vette engine is indeed its flat and wide torque curve. If you looks at the torque (or force) delivered to the wheels the M3 has higer values. It even has better peal values per vehicle weight. And because of the relatively llow rpms where peak torque and power occur in the Vette the torque to the ground curves really fall off early and dramatically (again compared with the M3). The M3 engine really allows broad and high torque to the wheels by its combination of of flat and broad torque curve combined with high torque multiplication through gearing. This goes a long way in addition to my other comments to explain performance similarities. All that being said in simulation and in all well controlled "apples to apples" straight line races the Vette will best the M3. As you and others stated the M3 is simply an over-achiever and the above is why.
Lastly, I clearly admitted the advantages of the Vette engine (and Vette engine stuffed in an M3) and that it would make the car superior in all times for 0-speed X contests. What is wrong with pointing out an interesting fact that there are still advantages and real advantages of the existing engine in the existing chassis? Sorry I guess I don't see that being out of place on m3post.com, nor being disingenuous. -1 on that Bruce.