Still not entirely sure what you are talking about. How easy it is to reach those buttons is entirely down to how you hold it, the size of your hands, and the proportionate length of your thumb.
With my small hands, it is usually a full grip or nearly full grip if I want to use both buttons.
I myself use the original Sensei mouse, still working all these years later. Though I have actually been eyeing that logitech wireless. I used to exclusively use wireless mice, even going back to the infrared days.