just to add, it's a decrease in saturation I'm seeing. As the colour space in PS and LR are the same and the file is the same, although "processed" into a tiff or psd (same result).
So I can't work out why there's a subtle drop in saturation.
ps. am I expecting too much? There is a sublte difference and it probably is highlighted when it's a "saturated" images.
Should an export to Photoshop, keeping the colour space (ProPhoto RGB) be an "EXACT" duplicate of the settings in Lightroom?