I can't speak specifically for Dacor, but since Dacor and Mares are the same company, I can speak for Mares.
I was on a dive trip last year with 8 other divers. We had 2 equipment failures - both were free-flowing Mares 1st stages. Scary.
And then my friend's Mares Ruby regulator has gone out on her twice now in the 3 years that she has owned it (once it free-flowed). And she goes on 2 dive trips per year with an annual service each year, so it is not being abused.
Lastly, the "remote" dive shops that I have been to have said very bad things about Mares/Dacor regulators. They tell me that they are very odd and require special tools. Oceanic, Scubapro, and other brands don't and are easier to fix. When I was in the Bay Islands off Honduras, one of the dive masters our boat could not find a local dive shop that could fix her Dacor regulator. So she ended up renting another regulator until parts could be special-ordered. Had she been in a large city in the USA, she could have found somebody to fix the regulator no problem. But in remote areas -- that's a different story.
So although my experience is far from "scientific", I've seen enough negative about the Mares line of products to warrant concern. And since Mares is Dacor, I would stay away from that brand as well. At least with regulators.
For regulators, stick with Scubapro, Oceanic, Atomic, Sherwood, or Apeks products. For BC's, go with Scubapro, Seaquest, Oceanic, Sherwood, or DiveRite. And with computers, check out Aeris, Oceanic, Suunto, or Sherwood. They are all better brands at equivalent prices to Mares/Dacor. And they all should be easier to service.
Of course, this is all my humble opinion.