nv2 does support QOS in its own way,
TDMA period size deals with that, as i understand that it will not exceed the tdma period size, cell radius also deals with that, as NV2 will reserve an addition time slot for "further" clients.
NV2 is aimed at P2MP environments but i have had great results on P2P connection.
The main difference with NV2 is that it does not adhere to waiting for a free time slot, but it pre-assigns time slots for devices, therefore it does not do a RTS CTS as with 802.11 that listens for the medium to be free, as with any wireless protocol a Clear Frequency is the key.
If this helped you then please slam that Karma