I haven't read through this whole thread but I thought I'd give an update on my ball python regurgitation issue. I changed up my male rotation and breeding schedule, so instead of pairing up and rotating males every five days with weekends off I pair up five days and then give them 3-5 days off. I'll separate and then feed and after feeding not handle any snake for at least 3-5 days. Seems to have stopped all of my regurgitation issues. Apparently some snakes were sensitive to being moved or paired up within 1-2 days after being fed. Problem solved!