Well, as I'm sure you know, the pentatonic scale is based off of the Major scale (the modes)...It is just lesser notes to get a different sound. If you know which mode from the pentatonic corresponds to every mode from the Major scale, you can throw in more notes that mesh well while still staying primarily in the pentatonic. Dave Gilmour seems to do that in his solos. I think the pentatonic is good for tapping, too. For some reason when you play ascending or descending runs on the pentatonic, it sounds more rock than blues to me. Hope that helps.