I just had a black heart installed on my custom. It replaced an Elkmaster. Before the elkmaster I was playing with a Kamui soft. And before that a moori medium. Before moori I used le pro for many, many years. I think it's important to figure out how does it feel to you. Let me explain.
I own a Fury cue with an Everest tip. The marketing behind Everest claims that it "hits like a medium, shapes like a hard, controls like a soft." Now the way it feels to me, well it feels hard. I don't like the way hard feels. I prefer soft.
I like to use the hardness rating scales. You can find them on Muellers, and Pool Dawg.
I try to stay as close to the 65 rating of the elkmaster.
The Kamui soft was good. But they did not last very long (3 months), and they lose their shape. I found moori and le pro very similar in terms of feel but the mooris held their shape better and lasted longer (a lot longer).
The black heart feels soft. I like it. My hope is that it last as long as the Mooris. If they can go 5 months I would be very happy.