yeah, I compared the both of them when I was in the market for a dosing pumps system. I heard great things about GHL Profilux Dosing and I was ready to order it and then Vertex Libra came out. I loved both but I went with Libra because it has touch screen, easily setup and update the firmware. There are two models: DC model or Stepper model.
I bought DC model when it just came out and it had some issues with firmware. It ran great and dosed accurately until Pump number 2 had mysterious overdose on May 19 2013. When I woke up, the 1.5 liter of Alkalinity left in 2.5 liter Vertex was gone. I contacted customer support from Proline Aquatics. They were amazing. I received calls from Canada team and Germany team and worked with them. They sent me new firmware and how to fix the vessels issue. Since than I have not had any issues.
DC model is a little loud. Overall, I really love it
