G'day Chris, having four would enhance the bending relief as you say, but as I said it comes down to economics, fuel burn is better with just two so I'm told, plus you don't have the capital and maintenance costs of four. Only need to wonder why twins are all the go, a 777 doing what a 747 used to do, though I'd much prefer to have four personally, ETOPs makes me curl my toes thinking of being reduced to one when may be 370 minutes from a runway. Bean counters rule.