Gipsy, you should say, "The published spin recovery for Firefly
usually works," because sometimes it doesn't. Read about all the T67 spin accidents--there's a lot of them.
Here is an interesting tidbit about the T67 and T-3A aircraft I just learned. T67's come with a small or large rudder. All the T-3A's came with the small rudder.
T67 with "Big Rudder"
T67 with "Small Rudder"
T-3A with "Small Rudder
Note how bottom edge of the T67 "big rudder" (first photo) follows the angle of the bottom of the empennage and so has about two inches of rudder below the trailing edge position light. The T-3A on the right has a smaller rudder that angles up to the position light.
If we estimate the bottom length of the rudder to be 14 inches that gives us: (14 x 2) / 2 = 14 square inches.
Fourteen square inches of additional rudder that's in the best possible location--mostly at the trailing edge below the elevator in clean airs during a spin. If I owned a T67 with the small rudder I'd look into replacing it with the larger rudder.
I noticed the April 2016 spin crash T67 has a small T-3A style rudder.
