After trying a few of the solutions listed here, my solution was to abandon ion-scroll all together and set overflow-scroll=true on the ion-content and then use a standard ul with the properties:
overflow-x: auto;
overflow-y: hidden ;
white-space: nowrap;
I actually noticed better performance on Android when I didn't use ion-scroll. And I could still scroll both vertically and horizontally and it performed exactly as expected.