We tried a similar one last summer by a different manufacturer. We have a 5x6 big round baler and 11ft discbine, so we are always doubling up rows before bailing. Using this type of rake speed up your time versus a single rake.
There were two things we didn't like about it and ended up not buying. First, it seemed to rope up hay instead of fluffing it into a windroll where it could get air and continue drying. It may be more for hay that's completely dry before you rake it. We like to let it finish drying for 1/2 a day in the windrow so we don't lose the leaves on alfalfa and clover mix. Second, it's kind of a big unit and hard to maneuver if you have small odd shaped fields like we have. We usually do 3 double rows around the outside and straight cuts with what's left. When raking the center rows, you have to lift the rake before the ends are done so you don't cut into the outside rows and leave these whale tail ends. Maybe we were doing it wrong and have to do the center of the field first and do outside last.
It didn't work out for us like we thought it would. We demoed it for a day, not to say we were using it correctly.