I tend to agree james. If you listen to Eruption, one of the speed picking licks there is lifted straight out of a widely used book of beginning violin excercises. As for the tapping, you're probably right. He incorporated some diatonic lines to his playing I seem to remember. I think the reason he doesn't get thought of as much when it comes to classically influenced players is because of all the things he did that were very much not at all classical. Whammy dives, power chord riffs, pinch harmonics, wierd animal noises, etc. You don't see as much of that in Rhoads' playing. Also, while he did play diatonic lines sometimes, more of his playing was pentatonic, and thus had a more rock sound than Rhoads' playing often did.