I fit the integral ones in the aqualisa quite a bit and they can go under the bath or in the loft and they are a lot quieter than adding in a shower pump. But like with all plumbing bits you get what you pay for. The more expensive it is the better it is and quieter it is.
Expensive but very easy to install. Hot and cold in , mixed water out all with ISO valves on inlets and outlet and easy push fits on to speed the job up.