I am experiencing the same problem with the same configuration.
While watching live traffic graphs of each ADSL connection, they hit about 2mbit each giving me a total throughput of 450kb/s or so.
Each connection individually can achieve 650kb/s+ at the same time.
I have disabled compression and encryption on both tunnels.
Any ideas on what can be wrong?
StevenJohns, Did you ever get yours working?