Soft Proofing clarification needed

On Page 67 of the New Piezography manual is this:

In Photoshop’s Proof Setup / Custom the ICC created in QTR for previewing is selected. The preserve
numbers, display options, and preview box are checked. The image on screen, if it changes abruptly in
contrast signals that the calibration to print is off. If the brightness of the image is reduced significantly by
the soft proof, then the calibration is too bright. It is a very good indicator of the calibration process that
was undertaken earlier.

However, in the blog post on soft proofing is:

To use the profiles in Photoshop
Go to View / Proof Setup / Custom menu on the Menu bar
In the Device to Simulate menu you can select one of the ICCs you have down loaded.
If you have trouble finding them – look for the ones that start with QTR (we used the QTR Create ICC software to produce these).
Set the Rendering Intent to Relative Colorimetric
Under Display Options check both of Simulate Paper Color and Simulate Black Ink
You can select OK to exit this window, or you can Save the setup so it is easily selected again under View / Proof Setup

My understanding is that Preserve RGB Numbers should be checked as there is no profile conversion during print. The Proof is to simulate how a PZ print will be printed. Am I correct in thinking that the manual is correct?

yes. preserve rgb numbers works best for soft proofing… and they are not used for printing.

Great, thanks Jon.