Most of the sliders implemented in both clients are infuriatingly vague or skittish. Skills, stats, macro delay, hues, sounds, etc.. they're all pretty horrible. At least my experience with them. I guess it's a personal preference.
I kind of like the buttons.. maybe add a slider between the buttons and make the number display type-able? Three ways to enter the number. So you could use slider, buttons or text entry.. like this:
<< < ----o---- > >> [##]
..you could click the >'s, slide the -o- or type over the #'s.