Does Rumple have a heart since he became the dark one?

I often wonder why the show never brought this up. Does Rumple still have his heart or when he became the dark one, did it disappear and all his love comes from his soul kinda like when Regina's heart got stolen by Zelena but she still managed to give Henry true love's kiss and still show love for Robin? Or is it possible that he does still have his heart but it cannot be taken out or it cannot be crushed? Or it can be crushed but it won't kill him and instead it makes him much much MUCH MUUUUCH more darker and evil and powerful and that's why no one dared to take it out?