Vey often I hear "I like to do in ACR all possible adjustments so that I save time in PS". Maybe I am wrong, but this aseveration doesn't seem brilliant to me; I could tell this person "I like to do in PS all possible adjustments so that I save time in my RAW developer":
This gets back to the guru who only understands Photoshop and doesn't understand rendering.
A Raw processor is a rendering engine. Its not a correction tool so to speak as we have in Photoshop. With Photoshop, you've got rendered, baked pixels. You can fix them but you can't re-render them. A Raw processor isn't as much a 'correction' tool as a rendering tool. There's a difference! Raw has no color, you create the color and tone from essentially Grayscale data. You do this by building metadata instructions that will eventually be used to build colored pixels that you may further need to edit in a pixel editor (Photoshop).
The beauty of metadata rendering is you have all the original data to work with that the camera captured.
You can build as many sets of instructions to render as many pixel based documents you wish in a truly non destructive manner.
You have linear encoded, high bit, potentially very wide gamut data to render. After rendering, you get what you get, you can't really put all that toothpaste back into the tube.
I'm sure I'm missing other useful features of instruction based rendering from Raw, but the big point is, its not pixel editing in Photoshop by a long shot. For this reason, the idea of doing as much work in CR than Photoshop makes a heck of a lot more sense in terms of quality, toolset and speed. Naturally there are all kinds of operations that can't happen until one has a pixel based document. Then Photoshop is king. Different tools for different tasks. Not the same as looking at these processes as a hammer in search of a nail.
It is here the guru doesn't get it. Worse, he says the toolset is unfit for professional use due to sloppy math despite Mark's continuing efforts to show that isn't at all the case. Meanwhile, getting Raws from the guru to illustrate his point have gone nowhere. Could be due not to sloppy math but sloppy rendering techiques? Where's the spreadsheet proving the faulty math?