So consensus seems there isnt enough difference in head shape/helmets to warrant getting a womens specific one?
Depends on the taste and head shape of the lady in question.
Womens' helmets seem to always have a visor which may have to do with them being more likely to sit "up" than men when riding.
The biggest issue seems to be the appearance factor though. Women are more likely to "need" a more compact helmet with less "mushroom" effect when worn. And for road helmets most of them seem to prefer it if they protrude less at the back.
Then there's colour/graphics and "ponytail exit port".
And finally size. Many of the smallest helmets are only in kids models with kids graphics. Many women need down to size 52/3. Standard sizes are 55-59 - it's not till you get to the mid-range that helmets are made in S/ML.
So basically if your wife has a head bigger than 55cm, hair too short for a ponytail and has no regard to what her helmet looks like, there is no reason to buy a women specific model.
I'm a big fan of Cratoni helmets btw.
Completed: 94 Stumpjumper w. M733; ; 92 Dave Yates 731 ; 97 Parkpre Pro-Elite ; Pace RC200 F6 ; Pace RC300; 82 Gios Super Record ; 97-8 De Rosa Giro D´Italia; ; Banani SPX Track bike ; 89 Alan/Mavic Cross Bike ; 05 Focus Cross Team ; 90 Look MI-80 all-Mavic ; 12 Focus Izalco Team/custom build ; 11 Focus Thunder Custom build
Projects : , Brouwer all-Mavic
Stripped : Pace RC303
Gone : GT Karakoram
Stayed in the family: Kuota Kharma, 04 Stumpjumper FSR
Ceased to be : Dynatech MT3, killed by corroded seatstays.