I bought this as a potential upgrade to a Meyer 5M, which I have had for years. I like the Meyer, which has a full, rich sounding low end and mid-range, but it does tend to sound thinner, brighter and a bit harsh in the upper register. I saw a comparison demo of the Meyer and a D'Addario on the Saxophone Academy YouTube channel which caught my attention and prompted me to try the D'Addario. I suggest you check it out before buying as it exactly reflects my experience having bought one.
The D'Addario is definitely a mouthpiece in the Meyer style and sounds quite similar, but it is much more consistent across the range of the instrument. The D'Addario is not so full and rich on the low notes as the Meyer, but it has a good solid sound and maintains it through the range of the instrument up to the highest notes. It does not become thin or harsh sounding in the higher register.
The mouthpiece seems to be very well made and accurately machined, as you would expect from a CNC made mouthpiece. It is a little more resistant than the Meyer, but not much. I bought a 6 and had no problem blowing it.
So, I would say that the Meyer and the D'Addario are both good mouthpieces, but they are different. I like them both for their particular characteristics.