I received my new O2 foot from Janome last week. It's the new 1/4" foot that replaces the O foot.
Janome made the new foot after getting comments from several Janome Horizon users that the O foot seemed to be a problem when sewing over seams.
The new O2 foot has the cutout on the back which allows it to move smoothly over the seams. I was impressed that Janome took customer feedback and made a new and improved foot. Everyone who purchased the Horizon before October and registers their machine online with Janome will receive the new foot.