I have used Opera mouse gestures for as long as they've been available (Wikipedia says April 2001 with Opera 5.10). That's a lot of years of muscle memory. These new visual mouse gestures make me wait on each mouse movement for that big graphic to show up. This slows me down tremendously. Also, the gestures seem to be much less tolerant of sloppy or angled gestures that used to work just fine for me. I've actually switched over to Chrome for a lot of my daily work because they don't put training wheels on their mouse gestures.