hfd - you are probably quite correct with reference to the ex-foreign air force aircraft. The ex-RAF ones may be slightly different, but RAF Bulldog spin techniques were learned the hard way.
People with sufficient experience for the type of aero courses you describe could probably cope with the dynamic entry techniques you allude to. The RAF had to ensure that the 'average Bloggs' could cope, hence the very regimented approach to the subject.
Having flown an ex-foreign air force Bulldog, I noticed that it seemed far quicker than one of HM's at the same power setting; perhaps both mass and centre of mass are significantly different?
I agree that it takes huge abuse to make the Bulldog spin off manoeuvre; the correct incipient recovery within the first 360 deg of undemanded roll rate stops the problem dead in its tracks! In fact the T67A is probably a very good aircraft for teaching aircraft handling on the edge of buffet nibble; its gentle but definite departures make the point very firmly. Not much use for serious aeros, but an excellent aircraft for teaching stall/spin avoidance - although it does take all day to get to a safe height for fully-developed spin training!