Thanks for starting this thread, it'll be interesting to see the results.
And thanks to ATHagan for including location and house temp/condition in your answer! The geographical area you are from probably plays a huge part in what humidity levels have the most success and is probably why there is such a wide range of humidity levels that result in successful hatches.
I've been running 35-45% humidity so far on my first hatch (I started at 50% but after more reading got nervous that that humidity may be too high so let the incubator "dry down" a bit). Out of 19 eggs that actually started developing, I've only had to toss one. Tomorrow is day 18 for us, and I plan on increasing humidity to about 60%. I live in central IL and the temps have been a bit crazy here. The first few days of incubation I've had to turn the air on to keep house temps under 80, but this past week or so I've had to turn the heat on to keep the house temp above 73. I believe the humidity in my house, or at least the room the incubator is in, is running around 30-35% because I stop loosing humidity when I open the incubator once it gets down to about 35% humidity. I'll be sure to check back in next week and let you know how my hatch went.