I had M-E and M8 side by side for several months. Barely find any difference.
Both are usable at ISO 2500 if you know how to do digital exposure.
Pictures looks the same.
M-E colors and else are nice, sometimes. But not always, to say at least.
M-E also pickups IR noise on hot days.
Batteries dies almost instant if it is freezing outside.
M240 has much more capacity in battery and it is weather sealed. Pictures wise here is nothing wrong with it.
M9 is kind of classic, M240 is still in production and sold for high price if new.