reading the benchmark from anandtech OMAP4460+SGX540 is also faster than Exynos 1.5GHz.
they compared the Exynos 1.5GHz with the OMAP4430 1GHz and there is no big difference in performance so the 4460 should be faster. In any case we will not lack performance.
Where are you seeing these? There are no benchmarks for Exynos at 1.5GHz nor OMAP4460, since no phones have been released with those SoCs.