Great post, Kev. I do my kits in a similar fashion, except that I use the "Levels" feature to create the color instead of Hue/Saturation. I find I have a lot more control over the colors that way.
I've found your method is also a good way of inserting monochromatic logos. What I do is copy/paste the logo from another file and position it on the shirt. Then I click on "Select All" and nudge the selection to get the selection edges to be the same shape as the logo. Then I copy/paste a section of the background onto a new layer, deleting the original logo.