I've built recommender systems at Etsy, among other places, and you get much better results if you make the data yes/no first. Shockingly MUCH better results. You'd think it would help to take into account, say how _many_ items of a shop a user likes, rather than just the fact that they liked some item, but it doesn't – it actively hurts. The only meaningful piece of information, it turns out is does this person like this thing or not.