Well I tried out both mice at BestBuy and I choose the MX Master. And I'm very happy with it. It's been a few days of heavy usage and no major complaints. It feels great in my hand. The M705 felt much better than my M510 but was just a little shorter on length and width. So just the bit of a bigger size on the MX Master was enough to make me go with it instead. The body of the MX Master is wider on the section that fit into the palm of your hand and that's probably what I like the best! I also got rid of my dirty old mouse pad as the laser works great on my wood desk. And I prefer a minimal look on my desk anyway. The side thumb button on the left, can be a bit awkward to hit. And the forward button is a little weird to naturally hit...