I picked up one of these Wednesday and I've been running it since then. I was worried at first because the instructions said the ideal ambient operating temp was 70 and I keep my house pretty warm in the summer (around 78) but it appears to be holding a stable temp. I will lose a degree every once in a while but it comes back up to temp quickly, and more importantly my digital thermometer hasn't registered a spike yet.
Without water the humidity ranges from 30% - 55% depending on if the A/C is on, so I think I may do the first 18 days without water and then add some at lockdown to bump it up for hatching.
I'll be setting eggs this weekend, it will be my first time with an incubator. I have a broody sitting on some eggs since last weekend. My thoughts are if she hatches what she has and does well with them, I may try to give her whatever chicks come from the incubator to raise.