These CPU's are very close in processing power ... Only other thoughts on an extra core with the Phenom would be if you wanted to use Core Affinity to allocate specific cores to specific tasks etc, so that instead of multitasking with all cores juggling the workload, you could specify an important task to not lag to have Core Affinity to give say 2 cores to a really important task and leave the 3rd core for the OS and web browser to function etc, and prioritize 2 of the 3 cores for crunching whatever task you need to have maximum processing power without competing with the other lesser important CPU use duties.
But as far as core affinity goes, I have only used it for playing older games built back before multiple core CPU's which act up when you give the game a 4 core CPU, in which for example the game Unreal Tournament 99 ( 1999 edition ) was made for Pentium III and Pentium 4 single core type systems and the game acts up with freeze framing with use of all 4 cores of my Athlon II x4 620 2.6Ghz quadcore, but the minute you set the core affinity to use Core 0 for the game and leave Cores 1,2,3 for everything else the game runs perfectly fine as if it was running on a single core CPU at 2.6Ghz