In my opinion the thing that makes our training the most difficult is the combined systems and maneuvers training. When I went through there was no dedicated time in the program to studying just systems because the Cockpit Systems Integration (CSI) phase focused not only on systems but also approaches and maneuvers. So you had to study for both simultaneously. If you don't have an organized plan on how to allocate your time and stick to it the volume of information presented at once will overwhelm you. But then that goes for any training program; at Spirit it's just quite a bit more so. Someone familiar with the current training syllabus should chime in here because I know they've made some changes since last May, possibly slightly expanding the timeline.

By the way, to the OP: I'm 90% sure you're the guy I was chatting with in Detroit this week. If you have any more questions feel free to PM me. Best of luck with your decision!