DD was enrolled in the original EPGY last year. It was ok, but she would get frustrated by lessons where it was assumed she'd already been taught the topic, but she hadn't--and there were no links to review earlier lessons (perhaps things she missed by starting in 5th grade math). She also LOATHED the racecar math facts "game" they're required to do.
The Redbird demo we tried seemed to be full of bugs and perhaps not ready for release. But that was a year ago, so perhaps they've fixed it. The issue I've heard about had nothing whatsoever to do with common core/not common core. "Common Core" is simply a set of guidelines for what kids should learn at each level, not so much how they'll learn them.
Anyway, DD still prefers Dreambox mixed with Khan Academy. I've heard the CTY math classes are good, but they're hecka expensive.
