You say you can do 'action' with MF
I didn't mean sports, but anything that moves even slightly such as a sitter for a portrait is unsuitable for stitching.
It is my argument that as an MFDB and SLR user the MFDB is much farther towards the still end than the sprinter end than many non MFDB users would imagine
Perhaps. I can't read their minds
In fact so far that an MFDB is inappropriate for many jobs - something that potential users should be aware of
It sounds as though your complaints are more against the MF cameras than the backs themselves. The only real limits of the backs as such are the limited sensitivity (compared with the best of 35mm DSLRs) and the slowish frame rate. Yes, people should be aware of this.
Yes they always render more pixels but this advantage is often outwieghed by lack of sharpness caused by movement or focus innacuacy
Again this seems to be an argument against medium format itself, because neither of those issues are due to the backs. It will depend on the shooting style, of course, but I never had these sorts of issues using Hass V or Mamiya 67.
To get a sharp image I either shoot tethered or take many frames - gently rocking to ensure one sharp one (or use huge amount of lights)
Which apertures are you experiencing these problems with? Which MF system are you using? Are you focussing manually? You have made several claims that it's so easy to get a blurred image with medium format, but that is either a problem with the AF or with your own manual focussing technique, or unsteady hands, etc. None of these issues are due to the DB.
Just trying to understand your disappointment.