I haven't ridden it, but I heard that the remaining section of the Springwater Cooridor past its official end in Boring to Estacada is indeed rideable. And the condition of it is about the same or maybe a little worse than the condition of the unpaved section between Boring and Gresham.
The one caveat is the bridges that are on this section are either gone or unpassable, so you'd have to portage your bike across the many streams that cross the route. There looks to be a creek on the Boring-to-Barton section, just a little north of 224. From Google Maps it doesn't look that wide, so it might be doable. But looking at a map and carrying a fully loaded bike down a slope, across a creek, and up another slope is another thing.