Sure worked well with coho, couldn't get enough. Easy too - just chopped up raw coho, onions, and garlic, and threw it in a big jar with apple cider vinegar and sugar (you can find some pointers online for the ratios), seemed to be best after about 10 days.
C-Run might be onto something, as some recipes called for salting the fish first and some don't, and I didn't salt. And Roger - I bet the high fat content of the chinook does factor in.
Until further evidence appears, I think I can definitely say stick to coho for pickling!