I don't know why people put Dinan on such a high level. Their products are way overpriced and not really anything special. Their operations is no different than any other speed/machine shop that makes their own products in house. I have been to their offices a few times and it always surprises me why people are willing to pay so much for their stuff.
Maybe back when there were very few tuners in the BMW market, they were great as a one-stop shop. But these days, they are definitely behind the curve and just banking on their brand recognition.