MSI don't source AIO's from Asetek anymore. Asetek have a patent that prevents people from using the pump on the CPU block design, hence why the pump is in the radiator. The Z series of radiators/AIO's under NZXT do have a pump in the radiator, meaning the OEM to that lineup isn't Asetek. At this moment of time, all AIO's with the pump in the radiator design are horrible.
There's no point in adding or Frankenstein'ing a radiator with another brands fans. The fans bundled with the AIO's cooling are adequate and at most times the best offered within that price point and performance.