Thanks Marty & Fiona for your thoughts. I too have historically favoured MHI for the same reasons listed (anyone would think we all came from the same uni with the similarity of our ideas!), but see a potential opportunity to expand and 'own' our role with VHI as a physio technique.
I think the paper that Marty was referring was: Berney, S. and L. Denehy (2002). "A comparison of the effects of manual and ventilator hyperinflation on static lung compliance and sputum production in intubated and ventilated intensive care patients." Physiotherapy Research International 7(2): 100-108.
I think there is scope to further research VHI, even if to only describe the technique and its usage and benefits in certain patients, and allow subsequent benchmarking.