IMO any amount of rollers will not stop syphoning.
I am not going to say anymore about the GHL doser on this thread in regards to whether you should choose it over another, as I am staying neutral but please do your research in the "relevant" places and I think you will be very impressed
But if you are going down the profiLux route as you have intermated then the GHL doser would be a natural addition if you are looking for a doser. No matter what controller you go for there is no point having a doser you cant control by your funky new controller.
However if you are not going down the controller route then you need to look for a doser with built in controller that can be expanded on easily, oops that will be the GHL then
Ok before I hear shouts of "hijack" Im outta here