However, it's no secret that few applications really require those ultra-fast MCU's. If a 12 MHz 12-clocker will do the job, there's little, though some, advantage in using a slower one-clocker, though it does save power.

It's been a while since I have seen a "12 MHz 12-clocker" being introduced and with chips getting EOLed just a few years after introduction, soon we will see max 4 clocks, min 36MHz being available.

The reduced geometries of todays chips makes the higher speed a "freebie"

Erik