I would say 3 Stacks with The Love Below?
As far as complete turns form hip-hop to singing; yeah. There's also Cee-Lo Green particularly his Gnarls Barkley project.
But beyond that there's always been hip-hop love songs and other "soft" soulful shit; from corny shit like Heavy D (that was hugely popular) to argually Method Man's biggest hit with I'll Be There For You. Rappers like 2pac were never really afraid of expressing emotion either.