As other posters have mentioned, one big drawback of the Dyson Airblade (stand alone unit) is that it's loud. 90 dBA loud [1]. I've never seen more than two Airblades in one restroom, with this combo unit, there could be double that number. That could lead to an unpleasant environment for guests of the establishment and potential OSHA violations for employees.
From using it, it appears to me that most of the noise is caused by the turbulence of the high-speed airflow interacting with hands and the enclosure (Fullerton's paper comes to the same conclusion). In that case, all you can really do to reduce the noise is reduce the flow speed, which reduces the effectiveness of the dyer action.