Good aren't they?
My usual mouthpiece is a PPT 9* - I have a 10* but keep going back to the 9* - and the overall sound across the range of the D'Addarios is not a million miles away from this. Not screamingly bright but not at all dull. My taste in tenor mouthpieces has mellowed a little over the years and I no longer go for too much ear burning (as represented by a Runyon Quantum 16 with spoiler). Interestingly, the alto's gone in the other direction.
They seemed very unfussy about what reeds were strapped to them - I tried Jazz Select from 2M to 3M, La Voz med and Alexander Superial Classique 3. All worked fine with relatively little alteration to the basic sound apart from the obvious - softer reeds sounding brighter on the narrower tips and vice versa.
All were very easy to control from ppp to fff and into altissimo.
Compared with the PPT they're a bit cleaner sounding (I know what I mean even if you don't 🙂) but the difference is really quite small and, if I didn't have the PPT, I'd be very happy to use one. I can certainly get what I would consider to be a "good tenor sound" out of them - loud, bright (but not too bright) and nice and fat.