We went into the Pratt filming this last Saturday. Definitely tough going. Lots of brush grown up, especially in the area where the trail leaves the river and connects with the railroad grade (area between "Halfway House" and "Big Trees" sign). Might want to consider long pants if going up the Pratt. After the Big Trees sign, it's clear going.
If you cross the river you are going to find some really rough brush to get to the trail. The trail is hard to find that goes to the river. We did not go on the section between Gateway Bridge and the Pratt but suspect that last mile (old logging road) is probably pretty brushy as well.
Whole thing kind of speaks well for fall and winter Pratt expeditions.