Yellow Springs is fine, Hamburg is really steep (gets you up on the ridge) and see a bit of traffic but people bike it all the time so they are used to seeing riders. Your other option would be Shookstown to Gambrill Park Rd, but it's still plenty of climbing. Rt 17 sees a little traffic but is not bad and mostly scenic. Overall your route is much better than 40/144. If you want less traffic pick up some of the smaller roads, but there are quite a few dirt roads out that way, so if you aren't into that you'll want to avoid them but I didn't notice any on the route you laid out. If you want to find where they are you can check dirtdata.org