Great reply as always Pima, but when you say "Ivy" do you actually mean very selective schools? The phrase "highly selective" might be more appropriate. The Ivies apply to only eight schools and don't include comparable highly selective schools like Stanford, Chicago, Wash U., MIT, Duke, Cal, UM, the Academies, etc. (some of these non-ivies are more selective than some Ivies, such as MIT and Stanford) - but if a high school had 25% going to these 4 yr schools but no Ivies, it would be darn impressive - I can't see a board penalizing a school in this case.
Also, I know you've mentioned that you heard differently, but saying that AFROTC looks at % going to an Ivy can send up a false alarm to applicants. Not all school profiles break out the % of grads attending Ivies (e.g., my kids' profiles don't and they both received AFROTC and NROTC scholarships). So, if an applicant reading this finds out from his or her counselor that their school doesn't provide this %, it might lead the student into over worrying. The profiles I've heard of or seen only include the schools their graduates have been accepted into, but not percentages - maybe an ROTC guy on the board who has seen school profiles can chime in on this.
Also, logically that breakout doesn't make sense. For one, that would be shortsighted by the AF because breaking schools into just Ivy and 4yr will sell some very good high schools schools short (for the reason mentioned above). Also, it is biased against poorer schools who's kids can't afford an Ivy tuition.