The downside of the partner hotels on property would be that the walking distance is too far and there aren't really any paths because of this. The shuttle buses get enormously crowded during peak times. Also, the hotels are not themed in Disney style, so if you like to be in the Disney bubble this could burst some of the magic. Other than that, the hotels are all good and clean and sometimes have better breakfast (more choices) comparing to the Disney hotels. But watch closely, because it happened to me more than once that Santa Fe/Cheyenne would be cheaper for us than a partner hotel on property.
Happy planning!