My area has been blessed this year, plenty of rain (I think it rained three times this past week, good size rain too). It doesn't mean the nectar is blooming right now (dearth) but Goldenrod should start up soon around here and take us home to the end.
For me, the largest issue with fall splits revolves around the dearth. I find you have to make them up stronger to bear through it.
Last year I made up a number of 2 and 3 frame medium splits in the beginning of July, with cells so they could make their own queens. I lost every single one of them. They just didn't have the populations to defend their hive, even with a .5" entrance, when the dearth set in and robbing took place. For that reason (among others) I've given up on all medium designs, and am going back to deeps.