I read in an article that the A6X beats out the Exynos 4 (a quad core like the Tegra) processor (used in the Samsung Galaxy Note 10.1) in most Geekbench tests; specifically, those that involve a single core. It's only in the multicore tests that the Exynos wins, but you have to consider that multicore performance rarely matters in tablet apps (for now, anyway).
I guess having more cores doesn't really matter unless there is a specialized purpose where it would matter.