sexing baby chicks

I am getting really confused...I have a mix of Orpingtons, Australorps, Wyandottes and Ameracaunas that are 2 weeks old. The threads that I am reading have the general consensus that the 'girls' feather out faster than the males. What I found with my now 8 week old Black Copper Marans is that the ones with more feathers... esp tail feathers, started to develop combs earlier and ended up to be the males in the pack. I am noticing that with my 2 week old chicks most of the ones with the longer wing feathers also have tail feathers and tend to be larger in size. The ones with the less developed wing feathers and no tail feathers also tend to be smaller in size... I would think that they would turn out to be female.
I assume that since I haven't seen any one write about sexing using wing feather development other than at 1-3 days old that it isn't an option once they get older.
I am going to have to find homes for about half of the chicks (15) and I want to be sure I end up with the mix of hens and roos that I want.
Any brilliant ideas out there?
Thanks in advance!

Feather sexing doesn't work after 1-2 days old and only on certain breeds. You can wait it out untill they are even older to find out who are roos and hens, you can also take some pics and put them in the what gender am I page, there are good tips on that page on how to take good photos for gender i.d. Lots of people are good at telling the gender by looks/pics on that forum.