Hi Peregrinacheena,
After just completing the CmnoNorte to Villaviciosa, then the Primitivo to Oviedo, Santiago, Finisterre, I would strongly advise against hiking boots. I started with boots, but then had to buy a pair of trail running shoes in Bibao due to the blisters caused by stiff soles and road walking. So many other pilgrims I encountered had similiar issues. If trail shoes worked well for you on the Frances, I would definitely stick with those for the Norte. You might have to be more careful about puddles, go slower on the slopes, and get a little wet and muddy, but in my humble opinion these are small trade-offs for the comfort of shoes on the long road-walking segments (even on the Primitvo). But of course, got with what is broken in and will be comfortable.
buen camino!