Thanks to everyone for contributions so far and special thanks to Grandad for answering my specific question. I would be interested to know what you put in the From/To section of your logbook when you have changed PIC.
Like Beagler I fly with a group and, being the least experienced and generally cautious pilot, I am conscious of flying into conditions (legal) which I would not do if I was solo. This could include a stronger crosswing than I have experienced so far. Knowing that I can formally transfer command without losing all of the precious time in the logbook will help me to be a safer pilot. The positive side of flying with more experienced, and qualified pilots, gives me useful experience which makes me a safer pilot when I am on my own.
One of the problems of less experienced pilots flying with more experienced passengers is that we tend to defer to their judgement. The only time I have been involved in damaging an aircraft was when I, as a RAF gliding instructor, was flying with the CFI for what is called a hangar landing i.e trying to end up as close to the hangar doors as possible. I deferred to his judgement on final turn and "we" broke the skid trying successfully to avoid going through the hedge.
I have also seen two experienced gliding instructors die together when they experienced a launch cable break which they had spent many years teaching students to cope with.
The scenario I raised initially describes a situation which develops slowly, there are many other situations which need instant action e.g. wind gradient on final approach, where a more experienced pilot may take control, and pilots like me might easily defer to them.