It's sheer coincidence that I opened your discussion, because I live in Palatine. It's all District 15, and overall District 15 students rate very well on statewide testing. Having said that, there are variations from school to school within the District. Some schools, particularly on the NE side of town, have a higher number of apartments within their boundary zones, and you do see the schools with more transient and bilingual populations, having somewhat lower test scores.
Unfortunately for some people who start off buying or building a home in "a perfect school area," things do change. The home you buy now could be "rezoned" into a different school by the time your kids get there (which may or may not be a good thing.) You might end up having an unexpected job change that causes you to move between now and then. I know that the administration can influence the overall tone/attitude of the teaching staff, as well as the students at any school. If you get a new principal at the school, who is responsible for hiring new instructors, or using a different curriculum, you're apt to see changes. My point is, there are no guarantees. But overall, most people find Palatine to be a desirable community in which to live.