The Dynaudio line gets a good amount of love here...
I bought the BM5As several months ago, as a replacement for switching between a pair of Alesis Monitor One (MkII) and M-Audio BM5a.
Both had major "holes" in their sound, in my room.
Happy I made the move - the Dynaudios are definitely more neutral (non-flattering AND non-detracting), and translate a lot better.
I had learned the other two pairs awfully well, so I'm still adjusting the the Dynaudios a bit... low-mid always seems to be a problem for me.
Anyways, really liking the Dynaudios so far, can't comment on the Yamaha model.