Only comment I can make is based on "exact match" traffic for French / France.
See
https://adwords.google.fr/select/KeywordToolExternal and choose "exact" from drop down box top right (note Google basically dominiates the search market for France).
1) For "exact match" local (France)
coiffures femmes - France local = zero (or close to zero) searches per month
coiffure femme - France local = 18100 searches per month
2) For "exact match" global results then is:-
coiffures femmes = 1000 searches per month
coiffure femme = 18100 searches per month
I think this perhaps answers the question of value between the two.
Hope comments are useful - cheers, Asiaplay
PS: but I am surprised that "coiffure femme" was sold as high as it was (interesting news for me - didn't realise traffic domains of that level reached those price levels for French).