Mark,
Plus point - every 3rd weekend off.
Minus point - always finishing on a late is tiring. I never feel fully rested by the time I come back to days again. We used to do 7/5/5/4 - transitioning to 6/4/7/4 meant we lost 44 hours rest in order to gain one 10 hour shift. The first days off are really "rest" days rather than "off".
We opted for it as the "least worst" rather than the best.