Thanks Alan - yes im a big fan of the deep blacks in general and 100% agree with you on the technology front. Think there is some confusion on a few of my posts that this is about shadow recovery which it is not. It was more to do with the noise in the deep blacks and how to get rid of it either through in camera technique or addressing any scanning concerns so that shadow areas render as pure black like I usually get if I enlarge in a darkroom print.
It seems that by switching from my rather elaborate old scanning method to the 16bit greyscale has helped somewhat and think improvement on the 'at time of capture' side of things will also help. As another comment suggested, might be down to the limitations of the scanner when its is effectively clear film base to deal with. It seems my older elaborate RGB 48bit DNG route might have done exactly what you suggested and along the way pushed the shadows up resulting in the unacceptably noisy black areas. Your previous comment was actually very help in coming to the realisation that some of these night time flash shots i've been trying might actually be generally very underexposed and that just because you can bump them up in PS (or as an accidental consequence in a long process) its best not to!