I wouldn't say these devices are 'hopeless' to configure, like everyone said it just takes a bit of time to get used to the NetDefend OS. It took me 3 days to get just the internet working, just because a DNS server wasn't available on the DFL-800. But with a bit of research and patience, you can achieve what you want.
If the device is 'too hard' to configure, just stick with a stock standard ADSL router.