I have additional information for you. I was working on someone else's computer this morning and it had a Logitech mouse (M705, don't know if still in current production, but it had programmable buttons.) So, I remembered this discussion and I checked with its control panel (SetPoint settings.) I saw speed controls for horizontal scroll (items #6 and 7 under "my mouse", left and right scroll, adjustable individually.) Which means that also Logitech mice can scroll horizontally. So, you probably don't even have to buy a new Microsoft touch mouse.
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