Why the Pennington-Wilson expansion with real coefficients is of little use in the analysis of production processes

We critically analyse and comment on the claims of M. R. Pennington and D. J. Wilson [arxiv:0711.3521]. Although we generally agree with their obvious algebra, it is clearly not applicable to our equations. Moreover, we argue that the corresponding proposal is not useful for production-data analysis. The advantages of our approach, which involves complex yet purely kinematical coefficients, are summarised.