Further digging in the "PowerBook" sections of my ever-useful old copies of The Macintosh Bible and Macintosh and Power Macintosh Secrets has revealed that the commentators du jour said that there was a significant penalty to be paid for active matrices over the old passive matrix screens. I should have known to look there before posting. No commentator, alas, quantifies the difference.

Apple's spec. sheets, however, effectively deny that there is any difference worth noting: the PowerBook 160 and 180, released at the same time and surely with an identical NiCad battery, both are said to get 2.5 to 3 hours from a charge.