If you want to run a herbie style overflow, I would recommend getting two of the Jebao DCP 6000 pumps. I have two of the 8000's on my setup but I was wanting about 1600gph without working the pumps too hard. You will definitely be able to get 1400gph out of two 6000's and not be working them hard at all.
Also, the reason I recommend these for the herbie style overflow is because the pump has 70 flow settings compared to the 10 available on the DCT and DCS. You can adjust it from 30% to 100% in single digit increments. It allows you to make really fine adjustments with the pump controller in order to achieve the proper siphon flow to keep the overflow completely silent. In addition, my DCP 8000 is running on setting 60 out of 100 and I can't hear it even if I try. They are very power efficient as my 8000 is currently only running about 35W (the controller displays the current watt usage right on it).
I will have to look into them. This move feels like its coming faster and faster with the amount of planning and learning I am going to have to do. Looks like I need to re adjust some things