I have never had a problem with any Laing D5 so far(1). I have had several Laing pumps and one of this specific model. It is quiet, has adequate(2) output, and the PWM mode works well. While NOT inexpensive, I have several Laing D5 pumps that are over 10 years old still going strong.
(1) I have had Laing DDC pumps fail. I do not recommend DDC pumps.
(2) The output of this pump is adequate but could certainly be better. I am getting a second one to be sure that I get adequate flow.