The Ad Hoc QoS mode setting (and all other Ad Hoc settings) will only affect your system if you are running an Ad Hoc network. If you are using a wireless router and your devices all connect to this router then you are using an "infrastructure" network. In an Ad Hoc network, all devices connect directly to each other without a router.
As far as I know, any device that has been WMM certified will automatically use WMM in an infrastructure network but perhaps there is a network administrator on here who knows for sure.
D