At the peak of their career, Sly & the Family Stone topped the charts with a Greatest Hits album – in 1970, it was their first LP to crack the Billboard Top 200, peaking at number two; an argument could be made that it was the LP that cemented their stardom – and over the years, they've been anthologized many times, almost each compilation worthwhile, but they've never been subjected to a comprehensive box set until Legacy's 2013 four-disc set Higher!…