We were there this year on the weekend and week after. Disney was very crowded but that seemed to be more from holiday people than the runners. We simply planned our days by avoiding the parks where the running was taking place and had no issues.
The only thing we noticed was that yes you needed to plan extra time in the morning for the buses, and I don’t mean 15 minutes extra. Not sure if it was the races, Coronado Springs, or just a general decrease in the quality of Disney transportation, but the buses were horrible. They just wouldn’t show up. You’d have 4 buses come through for the same location, and then an hour between buses for another location. We came close to missing a couple of ADR because of it, and I’m a plan extra time in type of person. We probably gave ourselves at least an hour of extra time each morning. For instance, if it was a 30 minute drive. I factored in another 30 to 45 minutes on top of that for getting to the bus stop, from the bus to park, through security, and then through the park to where we were going. Then I gave us another hour cushion just in case for delays on top of that. We usually left 2 hrs before we needed to be somewhere, and we were still late a few times.