I also use it (teacher TX = 14MZ 2.4 and student = 6EX 2.4 ). Works flawlessly. Only trouble is : don't try to change the link with another transmitter at the field, because any other powered-on radio will interfere.
Ask me how I know : both my sons fly mode 1 and I have for my best friend has a spare mode 2 6EX. [:@]

No idea if it works fine between different brands with futaba Tx module, but would not see why not... It definetely would not work when your teacher TX is another brand, as the WTR-7 cable will not fit

There's another benefit as well : if you plug out a (wire) teacher-trainer cable (accidently) when activated, you loose control of the model on both radios. This is not the case with the wireless link, it will return to the teacher radio taking full control no matter how you hold the switch. (Again : ask me how my sons' electric trainer got repaired so seriously and his father couldn't save it from hitting the deck )

Nicolas.