anyone used an induction heater for brazing?

lots of videos on youtube of people doing it.... could be handy, save lugging bottles around, easier to get into tight spaces, no worry about burning the surroundings etc.

couple of random youtube links...

5kw

https://www.youtube.com/watch?v=QZDKjV5SZGs

this one is 10kw...
https://www.youtube.com/watch?v=EHafYE82imc

guess it needs a pretty high power heater, I've seen 2.3kw heaters for sale - they can run from a standard UK plug... I wonder if that's too small and heat will be conducted away along the pipe quicker than it can heat it?