Obviously the 10 frame sprite *looks* nicer on its own, but the 8 frame sprite is definitely workable. The best judgment call really depends on how much work you want to do for all of your *other* animations (not just for your main char, but enemies/etc. too since consistency in animation speed/timing is a must!) This also depends on the frame rate you're going for in your game.
As for the sprite itself, the hair has just enough follow-through for being a little stiff, but not too much. The contrast in the shading in the legs/shirt could definitely be improved. Look at the contrast in the hair and try to match it closer to that contrast-wise because on darker monitors or on tablets/laptops in battery-saving modes, you wouldn't be able to see the shading in the jacket at all, and the pants you'd really have to look hard for it (even on my desktop, in which I'm viewing it right now!)
The animation doesn't have enough of a bend to the back leg which /kinda/ makes her appear she's jumping each step rather than just running. If you're going for a light jog as her upper-body suggests, you should consider varying the bend in the back leg just a bit more because her legs suggest she's in full sprint/run while her upper-body and hips suggest she's simply jogging. Hope this makes sense.