I am not an expert, so can only speak from personal experiance. In my case, one the couple of occasions where I was not quick enough with the rudder, the aeroplane did indeed enter a spin. However, at that altitude (starting at 6000') and in that aeroplane (Extra 300L) the recovery was no different from any of the others I've done. I have also done the same manoeuvre in the Pitts S2-C and DH Chipmunk, again with no difficulty getting out of the spin.
All I can think of (I also fly the T67M-160) is that in this aircraft, if you move the stick forward before applying opposite rudder, you can enter a "high rotational" spin (never done it myself). I understand that this can take longer and therefore much more altitude to recover from. Maybe the surprise of the spin contributed to this?
N.B. I was really not sure whether to add the last paragraph as it is pure conjecture, guesswork and filling in detail that I do not know....