It's me again, sorry
... I am sure it would have to make some difference if I was to select say, 72ppi and then tried to print big - wouldn't it?
As with most things in life, the answer is: it depends. If you select 72 ppi, move it to Photoshop and immediately
go to File>Print>Print... yes, there will be a difference: the print will be just a small section of the huge image (7D files @ 72 ppi result in a 48" x 72" printout... if your default page setup is Legal size paper, i.e., 8.5" x 11", you would have only 2-3 % of the image printed. Similar thing would happen if you insert an image in programs like Word: images with differently saved Output resolution (say one @ 72 ppi and another @ 600 ppi) would have different sizes on the page. However, no self-respecting Photoshop user would do such thing (i.e., open file and go File>Print>Print) without checking first the file size, desired print dimensions and output resolution. In such a case, the output resolution embedded by DPP (or any other converter) is indeed irrelevant, as you can (and should) always check it and change it accordingly.
Simply saving a file at different output resolutions does not change anything in the quality of the file, which is determined only by its pixel dimensions and not by the embedded output resolution.