I think Peerless is a great idea for portability, but I don’t use them for two reasons. First, they are a dye, not really a watercolor, so they stain and don’t lift like most watercolors, and they don’t move the same on the page because no gum arabic. The other thing is that the swatch does not re-wet – anywhere you have picked up color before is no longer “alive” so the swatches have to be replaced often. That being said, the brilliance of the color is great and a little goes a long way.
Be sure it doesn’t rain on your journal or sketchbook that has a sheet of Peerless swatches in it! Been there and it wasn’t pretty.