Another update
Bought a 2Wire 2700HGV (well two with one PSU).
I got a faster connection (1050kbps) but the router appears to lose connection after several hours. The log suggests its going to reconnect, but it doesn't actually seem to do so automatically. I reconnect it, it works for a while - then dies.
Watching the stats it seems to be very aggressive at trying to drop my SNR so I suspect that it's just too aggressive for the line? Confused why it can't reconnect though. I've tried 2 units, both with different firmware versions. Same PSU with both, though.
Back on the Billion 8800NL and getting 800kbps.
Both were using ADSL (G DMT). Will try using ADSL2 later.
I forgot to mention - my DSLAM is Infineon. I've seen online that supposedly your better matching vendors. My Billion is broadcom but the 2Wire used an Infineon chip. Any other good Infineon ones?