MikeJ
Most of the accidents involving civilian operated ex-mil Fireflys in the UK have been spin/aeros related. The spinning characteristics of the aircraft have been discussed already in this thread, and so I won't add to them other than to reinforce that the aircraft may enter a high-rotational spin if the full spin recovery is mishandled, and that it will not recovery from this high-rot mode unless the correct inputs are made. It's not a Cessna 152; if the Firefly is high-rotational it will be going all the way to the point of impact unless the correct drills are used.
It will depart quite suddenly during aeros if pulled through the heavy buffet, but will recover quickly if incipient spin recovery inputs are made promptly. A possible scenario with an inexperienced pilot could be to inadvertantly pull through the heavy buffet on the second hand of a loop with undemanded roll developing quickly into a full spin followed by a moment's confusion leading to the stick being moved forward with yaw rate present and no opposite rudder. In this scenario the aircraft will quite possibly have gone from a loop into a high-rotational spin in 5 seconds of tumbling horizon, varying 'g' and a buffeting stick. A successful outcome then requires either a calm, properly-trained head or a servicable parachute.
The Firefly is a safe and competent aeroplane (yeah, except the roll-rate, I agree). There are no issues to be addressed IMO, other than to ensure proper training and currency for those intending to turn them upside down.