intec and Adtran have working parts for testing bonding. 35b uses double the spectrum for double the speed, 200+ megabits at 500 meters. It's not ready for the field yet, but test gear is now available from the German firm intec. Look for them at the Broadband Forum Interop exhibit.
Jeff Waldhuter of Verizon told me not investing in testing was the biggest mistake they made in the early days of DSL. BBWF will also feature Lincoln Lavoie, who has led the UNH/Broadband Forum testing for years. You can now buy the testing software they use for your own work. UNH uses Telebyte hardware, who will speak at the show.