Interesting, I've not heard of that particular REAR LINE method before.
Funnily enough I uploaded a video a couple of hours ago of a hot launch technique, although the video mainly concerns itself with a DIY 'anemometer vane' for use in kite buggying.
I got the hot launch idea from Genetrix who claim they can safely hot launch the Hydra due to it's very wide wind range and Supported Profile System where the bridles actually attach to the the struts but they do warn that this method should NEVER
be used with any other inflatable. The Genetrix Hydra is the only LEI to use SPS.
Genetrix' method is I assume only a demonstration of its depower range and supported canopy and probably not recommended for everyday riding. You can hear the lines whip as it takes off which sounds cool but it might be putting the kite under unnecessary stress. If you have the usual option to launch then I'd use that.
How safe it is for teaching students ? Personally I think it is a bad habit to get into as the hot launch requires upwind rigging which can lead to back lines threading though front lines as I did yesterday. Lines are easier to inspect when laid out downwind.
Hot launching will benefit me for sure in low gusty inland wind where the kite refuses to sit up at the edge, but I'll still solo launch my kite in the usual ways if I can.