I agree with you about precaching - Adobe's service is one of the reasons I gave up on AR 7. No matter how many times I disabled it, it just kept coming back, like the Energizer bunny! The other reason, had to do with using AR 7 as the default in-line reader is both Firefox and Maxthon and its instability. Foxit is much more stable in my usage.
With reference to Adobe precaching, I DID find, that with the service running load times were very quick, hence my decision to ditch AR Speed-up. You're right, though, in that the two approaches are very different.