Im deploying Intermec terminals (2455's) in my wireless environment. The terminals are MAC authenticating back to a local ACS server and are configured with 128 bit static WEP keys. The access points are all 1200's on the same network segment and running 12.02T1 version of firmware. The access points are all configured as root access points and hard wired into Catalyst 3500 switches.
The problem I have is with roaming. When these devices roam they typically drop a few packets (observed by continuous ping) and roam seamlessly to the user but often times the device will "time out" for several minutes. The access point shows that the device is associated, but again, the device cannot communicate. I have several aeronet clients and workgroup bridges in the same environment which roam without interruption.
We had similar problems (and still do to some extent) with LXE/PSC devices. One thing that fixed our issue was turning off PowerManagement on the client adapter. It was "going to sleep" and during that time losing packets which resulted in a disconnect from the host. We are told it is a flaw in the DOS driver or the IP stack (depends who you ask). And that would seem accurate, since none of our Windows based wireless clients get disconnected.