They are hyper loaded on nutrition,Kale is a powerhouse food so I'd say return on investment is high.
I just hit em in the oven,1-2 trays go plenty fast and thats a
lot of chips,smoking does look like an awful lot of work.
Takes 20-30 minutes at 325F in oven but times vary based on kale and moisture,some take even less,Mrs does 1 tray at a time (about 2 servings for me from one bunch of kale,thats a lot of Kale IMO)
LOOSELY piled high is about 2 bunches of kale per cookie tray (why do it slow,it shrinks down says Mrs).Every load is different.Just a light spray with EVOO on pan,and spray/spread it lightly and evenly well among the leaves.Sometimes we move em around as they cook for more even drying,optional.
We either sea salt (or spice you choose) is important for flavor before oven time.Nutritional yeast is yummy after they've been cooked,has a salty cheesy taste(some we do,some we dont),might be an acquired taste,I liked it from the get-go very much,I like salty things.Its also really good on popcorn.They say its good for you too,but I like it just from the flavor aspect.
Im not so sure if doing the mixed greens is what you want either,I dont like collards or especially mustard at all unless cooked.I think you'd be much happier done as above.