Damn you guys are good!
That paper by David Rogers is printing as I type - something to read over lunch today I think, and I shall try from my end to get hold of that Transport Canada document.
A note to 212man; the RAF I know used to teach turnbacks as a matter of course. I think that these were finally killed off circa 1994 after a Hawk with a QFI+QWI crew with about 6000 hours between them landed on a wingtip at Valley at the end of a practice turnback. This led to the realisation that HMQ was losing more jets practicing turnbacks than she saved by having crews current in the practice and I believe they were banned. I'm not sure how this related to Bulldog practices (possibly your local OP was based upon minimising risk to third parties?). But, one point you mentioned rings true with my own experiments - I've found that nibbling the stall warning always gave the least poor chance of getting away with it. That seems to be borne out by the conclusions in Rogers' paper too, who advocates turning at 45° of bank and 5% above the stall speed in the turn.
G