TTHills, As you say, it's not unduly hard, but it also won't respond to small adjustments. When it gets down to lower groundspeeds it can take full rudder deflection and sometimes brake to keep the swing from developing. Hence you'll often see a Pitts' rudder flapping back and forth quite a bit in the waning moments of the rollout.
DAR, I'll guessing that DC-3 momentum problem is exaserbated by having no propwash over the tail, too?