Treg, the bosun's chair is standard equipment for UK SAR winchmen and has been around for many, many years. It is essentially a seat/nappy harness that puts the winchman in a half-seated position when on the wire and is much more comfortable than using a strop.
A genuine question for all: if a loved one of yours sustained similar injury and there was no alternative but to conduct a high winch, would you recommend a single or double strop winch?
double strop every time, it is much more comfortable, especially for the larger person. Our strops have a 300lb limit so the 130kg (286lb) casualty would come very close - using 2 strops spreads the weight and allows winching of bariatric (read fat!) casualties.
Additionally, should crews that only practice live winching at height not above 15', in an area where forced landing must be achievable, be tasked to conduct high winches over steep and heavily treed terrain?
that is a question for those who pay for this service - is it reasonable to ask crews to perform rescues that they don't train for? Appropriate training is the only way to mitigate the risks involved so you either take some risks in training or leave it all to the real rescues and then wonder why you have incidents.
There is always some value in analyzing incidents such as this but 20/20 hindsight is usually too harsh when questioning the decisions of the crew on the day. They had to make the calls based on the situation they faced with the information they had - that is the nature of SAR.