I'll post some more brief impressions of the M11 now that I had the time to listen for a bit.
It seems like they sound better from a shallow insertion, which increases the soundstage, without affecting the sound adversely in other ways. I don't notice a significant change in isolation from shallow vs deep insertion. What it does do, however, is make them even more comfortable. Incidentally, I should note that I have tried the klipsch S4 for a couple of weeks and own the PL50. Both are known as extremely comfortable IEMs, but the M11 actually surpass both in terms of comfort. This was a very pleasant surprise when I first put them on, and is a very significant plus in my book.
Also, they seem to be either a) less efficient than my other IEMs or b) simply sound better at louder volumes. On my sansa clip, my music is normalized to 89db. With the pl50 I would normally listen to it at 1 (minimum volume). At most, I would hit 2 or 3 if it was very loud around me. With the M11...I'm listening at 8-10...and that's at home where it is quiet.