I have to say I like the look and the idea of the plastic edging best and the added protection it gives. I decided to skip it on mine, just sanding the edges with an orbital sander w/80 grit or so. The corner gets covered with canvas and TBII twice since the top and sides lap over it by several inches. It's reasonably stiff.
A few reasons I prefer canvas is it's just much quicker, I'm 57 years old and am really enjoying camping and exploring
and not spending lots of time building a camper. Also any repair big or small would be easiest on just canvas corners.
I am uneasy with all the different materials all glued together and subjected to heat/cold cycling from the weather. Foam, pva glue and primer, vinyl(?) edging, spackling, if it doesn't stay stuck or gets a good thump it would not be easy to fix.
But, I really have no real life experience with such on a foamie. I hope others will let us know how things fare.