Ah yes, to slip or not to slip, the perennial question...
Each has it's advantages, which I'm still learning about. Apparently, not slipping can make for the nicest, most invisible seams, on medium weight yarn. I've yet to try this.
I have always slipped, but I may change my mind when I experiment more with seaming and not slipping. Also, I want to experiment more with picking up stitches on a non-slipped edge. You can pick up stitches quite nicely on a slipped edge, if done properly, but it can be a neusance to find the proper hole to pick up alternate stitches in, unless you're picking up only one stitch for two rows, then it's a breeze.
For stockinette selvedges that won't be sewn, I definitely like the slipped edge look.
It's really a personal preference. People swear by both!
For that pattern, with that fuzzy yarn, slipping makes perfect sense, because it's easier to sew up, and you won't notice a gap from only doing one stitch every 2 rows.
KnittingHelp Queen Bee
"There is a vitality, a life force, an energy, a quickening that is translated through you into action, and because there is only one of you in all of time, this expression is unique. And if you block it, it will never exist through any other medium and it will be lost. The world will not have it. It is not your business to determine how good it is nor how valuable nor how it compares with other expressions. It is your business to keep it yours clearly and directly, to keep the channel open. You do not even have to believe in yourself or your work. You have to keep yourself open and aware to the urges that motivate you. Keep the channel open."
— Martha Graham