Probably. Assuming I've understood you correctly,
You're wanting to connect clients wired or wirelessly to your network and control their access into your network? You're not wanting to have to bother about what they connect onto that network.
Well if that's the case, I haven't used 802.1x to achieve this. What I do is just install DD-WRT onto a router and connect that to the network. As it has a built in firewall I can do any filtering required on the device which will apply to all users connected onto it.
If it's a remote office, no problem. I set up a VPN tunnel using DD-WRT's OpenVPN client.
The effect is the same.
If it's a remote office and their have their own WAN and you're needing devices on the downstream side to access services inside your network then you can use static routes on the DDWRT router for those specific addresses to go through your VPN, otherwise out the normal network gateway.
So, if that's what you're after then I can recommend you find yourself a router that can run DD-WRT and have a play with it. They advertise good support for Buffalo routers. Best of all, DD-WRT is free.
Just confirmed. DD-WRT can authenticate using Radius, although I've not used it an ex collegue tells me that it works really well. So yes, if you're looking for a device, any router capable of running DD-WRT or Open-WRT will probably do the job.