I just know that in MA when I raised RIR I incubated closer to 98.5-99.5F and had great hatches, but when I used that previous experience down here in GA with eggs from a friend's mixed flock, it was disastrous. With the current batch I went higher and have had far more success thus far. Only 2/6 eggs (started with 9, but not counting three because they'd been hidden by a broody) made it two weeks and this batch I currently have 6/8 with one being infertile.