A wireless trigger separates the flash's circuit from the camera, so a possible high voltage cannot damage the camera. Of course the receiver connected to the flash can be damaged instead, but the consequence is that only the receiver will be destroyed and that is not very costly. I use YongNuo flash triggers, type RF-602. These were intended for Nikon but also work on my NEX-6 as well as on the Panasonic GH2 and G1 in combination with Falcon SS-150 studio flashes. Although I have several flashes with trigger voltages well over 250 V, I've never tried to use those with the trigger system.
The only way to know for sure is to measure the voltage at the sync terminal of the flash with preferably a digital multimeter. If the voltage is 6 V or lower, you should be safe. The YongNuo transmitter (3 V) and an Olympus FL-50R (4.5 V) did not fry my NEX-6.
