Yes, the F-ED had ED glass. I'm sure there's some changes in glass characteristics. The problem with labeling models ED/HD/etc. is that a lot of that is based in marketing and nothing else - two types of ED glass can have very different performance. The M2 has been upgraded with a magnesium body and is over a pound lighter.

The M2 is supposed to come with a camera adapter, so there's that. I'll post more when the preorders arrive (scheduled for today).