My Teac firewire CD-RW (SmartDisk VST) drive works fine with a benh kernel. It seems to burn at a slower speed than it does under os x, but I haven't done any actualtiming tests.
I have the same device and cannot confirm this. The drive is slower for CD-RW than for CD-ROM, but speeds are the same in linux and macos X. Perhaps you did not set the maximal speed with cdrecord. -gaudenz