I have 2 WANS into my Balance 20 a theoretical 5mb/sec down, 512k up DSL connection and a theoretical 8mb/down 3mb/up wireless link.
The DSL link is pretty variable with average speeds being 2-2.5mb down, 128k up and the wireless link does 7mb down most of the time but occasionally crashes hard and ends up with 100k down/10k up.
It would be nice when it comes to troubleshooting the connections to be able to run a speed test from the admin page. As it is I have to disconnect each connection manually, then goto speedtest.net to run a test, then reconnect and disconnect the other.