I've been shooting Blackdots (among others such as OBs and Pechauer Pros) for decades. I like them overall. They have a 'soft hit' which is probably due more to the actual taper than how the shaft is constructed, and from one Meucci blackdot to the next they feel pretty consistent.
They do feel kind of 'dead' though. I don't feel like there's as much feedback with a Blackdot as there is with a true solid maple shaft, for whatever reason. The Meucci Originals that I owned all seemed to feel more 'live,' if you will. But shoot them one after the other, and you can easily see the difference between a solid maple shaft and a Blackdot shooting any kind of english on the ball.
However, Blackdots are kind of old tech, if you will. Compared to today's "low deflection" shafts, Blackdots probably deflect a little more than most of them. But if all you've shot is solid maple shafts, then a Blackdot will be an improvement as deflection goes, generally speaking.
Compared to a Red dot, the Black dot seems to deflect less. But the Red dot has more feel or feedback, and it's easier to do certain things with a Red dot. Masse for example or even small jumps. Black dots can masse, but don't really jump all that well.