After acquiring some 2nd hand routers, I felt inspired and dug out the old laptop to have a tinker, and was curious how the BT5 series was doing.

Some interesting figures regarding aireplay-ng injection though...
All tests were conducted on the same AP

Cards used
ath5k Cisco aironet AIR-CB21AG-E-K9 (cardbus)
zd1211rw Buffalo WLI-U2-KG54L (usb)
rt2800usb Alfa AWUS036NEH (usb)


Code:
BT4 - 2.6.30.9 vanilla & 2.6.34 hand rolled
Same results with vanilla drivers, and compat-wireless 3.5rc3-1 (patched) tested

Driver           Packet rate laptop/VM 
ath5k               700 pps/no PCMCIA slot
zd1211rw            1000pps/800pps
rt2800usb      not tested on physical hardware & device fails to work correctly in a VM ( AWUS036NEH )
Enough IVs to crack within 5 minutes.

-----------------------------------------------

BT5 - R1 & R2 
Vanilla drivers & compat-wireless 3.5rc3-1 (patched) tested

Driver             Packet rate laptop/VM
ath5k                   50pps/no PCMCIA slot
zd1211rw                50pps/50pps
rt2800usb               50pps/50pps
Takes well over 25 minutes to gather enough IVs to crack

Note, on BT5 (r1/r2) aireplay output states its packet rate is hitting 1000 (or whatever I fix it to) but aireplay 'sent packet' count is only creeping up somewhere around the 50pps rate.
If checked with airodump, you can clearly see the data rate of replies is incredibly low.
I've also tried fixing the packet-rate to 150 to lower the load & see if there is any change, but its still remains around 50pps

Also, some other things to note,
when using Alfa AWUS036NEH with rt2800usb driver on BT5R2, rmmod/modprobe -r rt2800usb hangs Backtrack completely, requiring a hard reset.
Unplugging the device is the only way the driver can be unloaded without hanging. This is the same on both physical hardware, and a VM.

VM & AWUS036NEH do not like each other much, monitor mode is available, but refuses to collect any data, or inject. (all versions of BT, stock drivers & up to date+patched compat-wireless tested)
BTR2 reports incorrect max TXpower for AWUS036NEH, on R2 it can only be set to 27dbm, all other versions (4/5r1) support setting at 30dbm (1000mw)

BT5 r1/r2 was tested from both live DVDs, and updated installs.


So, I guess what I'm interested in the most, is what happened between BT4 and BT5 regarding injection speeds?