I might have missed it but I don't see where SimonS mentions what specific printer he has.
His screen grab shows he's using a Canon iP4700. No plug-in for that, AFAIK.
But, I do know with the iPF printers that if PSCS5, ACPU, or i1Profiler 1.2 were not listed in the special cases file I would be seeing the same issues when printing targets.
Yes, true, and thanks for all your help with the XML files. Again, this is one more reason to use the PS Plug-in when profiling iPF printers if possible.
My experience with null transformation were with Epson printers when this issue brought about by changes in the OS first occurred. So in PSCS5 are you choosing Photoshop Manages Color or Printer Manages Color when sending a null transformed target.
Just to clarify, one needs to use "Photoshop Manages Color", AdobeRGB, RelCol, noBPC with a target that has AdobeRGB assigned to it, for RGB managed printers (inkjets mostly).