I have a TT1 and five TT5 units. I think the Hypersync speeds depend on the camera body. They do reliably trigger all of my strobes at 1/400 with a 1D2 body in Hypersync mode.
(For those who haven't seen these, the Hypersync mode triggers the flash slightly before the shutter opens, allowing full power flash at slightly faster sync speeds. This is not the same as high-speed focal plane sync mode, though the new PWs will do that, too.)