I've an EDIMAX EW7318-usg and the module rt73usb (Debian Lenny put this instead of the old one, rt73). I did the test to check injection (aireplay-ng -9 wlan0), and it works perfect.
I decided to try aireplay in my essid (RXQ high of course), and I could associated inmediately (in my rt2500 it needed some tries). But when I try to inject (aireplay -3 ...), it only read packets, no detect any ARP|ACK replay. I 've tried disassociating (aireplay -0 1 ...), with my other computer associated and trying to inject with it... noting.
I'm very confused because it seems to work great this card with this module, but at the moment, it seems only. At the moment of truth, it doesn't get ARP | ACK replays..., and this is almost impossble because I disassociate clients...
I'll try the old ones rt73, and I'll comment the result
I tried with rt73, and finally I got injection. I had to do with a connect client, because it was impossible without clients (it cuouldn't associate).
With the same conditions, I tried rt73usb. And it work injection!!! But I have to say the injection was very slow. rt73 injects with high speed. rt73usb slow
When I connected with rt73usb to the wlan, it made something strange. The start pool of the dhcp in the router starts with 33 (192.168.1.33). There was one connected client. The IP offered by router was 34, but rt73usb got 119 (192.168.1.119).
When I pinged the router, some packets (half of them more or less) were lost. The connection was very slow.
With rt73 the connection was very good.
To sum up
rt73 is very stable, and it works great the injection (with my card it takes long time until it injects). rt73usb follows some rules as only allow to change mode with the card down..., but is still testing. It should improve with injection and connection