Have "Riot Going On" and "Greatest Hits" on RtR... Sly was massively talented and the band had a truly unique sound... Coke did him in, if my memory is correct. He got hooked so bad that it cost him his band, his record contract and he basically fried his brain. His former label then screwed him over on past royalties, etc. because they knew he wasn't all there mentally anymore and wasn't in any position to challenge them.
Attempted a comeback in the late 70s / early 80s but the mojo and talent level was no longer the same. Truly sad. May he RIP