Define regular user? You've already looked at the benchmarks and have a good idea of what software benefits from extra cores. Games, word documents, internet browsing, music, movie watching, and a whole list of other things most people do will not benefit going from 3 to 6 cores. 3ds max is 3d software frequently used for game design and computer graphics in general, it's a rendering benchmark. Cinebench unless I'm mistaken is just another synthetic that shows general performance difference if you have software that will use all the cores, and I think POV is another render/video encode type test, not sure off the top of my head.
Basically most tasks won't use the 6 cores, if you know your not running software that can, you probably have no reason to upgrade.