Quick update: Today, for the first time, I pulled off a score of 60 WPM on TypeRacer. The passage was pretty short, and this is definitely an isolated event, but I'm pleased with my progress.
More consistently, I'm hovering around the 40 WPM mark, with occasional dips into the 30's and rarely 20's on the more difficult passages. IM'ing has progressively become easier and more manageable.
Gotta keep on keeping on.