The Mega STE is my favorite Atari ST for many reasons. It is highly compatible with most software, but runs things faster due to its 16Mhz 68000 with 16KB cache. The external keyboard is a great improvement over the traditional ST keyboard, and it is easily expandable.
The Mega STE is somewhat rare, however, so if you’ve never run into one in the wild, here are some of my favorite “secrets” and facts about it that you might find interesting.
By default it boots up in 8Mhz mode for maximum compatibility. To switch it to 16Mhz mode, you typically need to use the XControl panel accessory and save settings. But you can also use a small program in the AUTO folder, such as MSTECPCL by Peter Putnik, to boot into 16Mhz.