I can answer this, sorta. As an ALO I work with all manner of candidates. Several years ago (more than that, the guy is a junor captain now) I had a candidate that enlisted in the AF, did a superb job as a young airman, went through the LEAD (Leaders Encouraging Airman Development) program, was selected for USAFA's prep school, did that, and then went to USAFA.
I asked him one time: which was harder, BMT, PS BCCT, or USAFA BCT? He hemmed and hawed and said for him, BMT was because he was right out of high school and didn't know what was coming. He knew after that and found that the PS and USAFA, while challenging, weren't really "tough" for him. Of course he was in pretty excellent physical condition by then too.
That's the only example I have for you; if others have experiences to share, I hope they will!
Steve
USAFA ALO