Ted Brewer is in Good Old Boat this month, with his 'Thoughts on sail plans'.
He is mainly advocating the 3/4 rig, but one of his points is that the CCA rule drove boats of our vintage to carry a higher ratio of headsail to main, and that this was a less efficient sail plan. The evidence he cites is the 5.5m class in the 60's where he says the rules were different and all boats eventually '"flew the minimum-size jib and maximum headsail as any other distribution of sail area resulted in a losing boat."
Kinda makes sense, that the overlap would be less efficient.
I wonder if a partially furled 155 could ever be faster then an unfurled 155?