You don't HAVE to change the suite settings unless you want to. You can Edit > ASSIGN (not Convert) Profiles... and assign the correct profile to the document and your previews will reflect the new spaces. Just keep in mind that if you still have the old settings in place for the other applications, you may convert to the wrong profile if you do things like simply changing the color mode in Photoshop instead of Convert to Profile from the Edit menu.
When working in indesign what should i do when working with jobs intended for Uncoated and Coated stocks should i be changing my suite colour settings depending on the job each time?
Do you mean you have one job that will be printed on both coated and uncoated? If that's the case you would want to avoid CMYK color and consider placing RGB, then you could have one ID doc which is exported to two different CMYK destinations—coated and uncoated.
The CMYK profile comes into play when you make any color conversion to or from CMYK, so Fogra Coated will display CMYK color differently than Fogra Uncoated because there needs to be a conversion to RGB in order to display CMYK. Likewise the CMYK numbers you get when you convert from RGB to CMYK will be different depending on the destination CMYK profile—different profiles can produce very different CMYK numbers.
A printer once told me that, for PANTONE at least, there is no difference between coated and uncoated. The different libraries are for screen display to show what a given PANTONE color will look like on the respective stock, and indeed they do look different in an InDesign document. However, when it comes time to mix the ink for the press, the formula is the same. In other words, there is no such thing as a coated ink and an uncoated ink.
I would like someone who knows for sure to confirm or refute this.
If it is true, then you can leave a document built with uncoated inks, but destined to print on coated stock, alone. The risk comes in using both a coated and an uncoated swatch of the same ink. It will count as two spot colors and give you two plates, which is not what you want.
That's correct. The inks (both spot and process) are the same regardless of the stock. The profile issue though, is not really relevant to using spot colors, but comes into play when converting colors to CMYK and achieving the best possible results. Coated stocks have lower dot gain than uncoated, in general, and the formula used to get the same APPEARANCE of a particualr color will be different for each stock. Wit spot colors you don't really get the option of matching appearance across different papers.
If the job is not CMYK and the Pantone colors are to be separated as spot colors then the only output difference between Pantone 172 C and Pantone 172 U would be the label on the plate or film.
If you are using the Pantone Solid libraries to pick process CMYK colors (not a great idea) then the color preview and CMYK output depends on whether you have Use Standard Lab Values for Spots checked in Ink Manger (Photoshop uses the Lab definitions).
If it is unchecked then Pantone's CMYK color builds are output unchanged IF your destination is Document CMYK at export or print time. In that case the preview of the color would depend on your doc's CMYK profile. If you use some other destination there would be a CMYK-to-CMYK conversion at output and you would not get Pantone's builds—which are the same for coated and uncoated.
If Lab is checked you get a color managed version of the color—the previews and Lab definitions of Pantone 172 C and Pantone 172 U are different with Lab checked. With definitions as Lab a color’s preview doesn't get clipped by the CMYK gamut and the doc's CMYK profile has no affect on the preview. If you print or export the Lab swatch to CMYK, there is a color managed conversion to your CMYK destination—you'll never get Pantone's CMYK recipes with Lab checked.