Just a word of warning on using the electric elements in the keg as a boiler.
When new and you put them in, also put a heap of silicone tape (heat proof) around the cable at the join that connects the cable to the element.
This help elimate the play in the cable when moving and washing the keg.
On one of mine, because of the play in the cable, melted the wires together.
Mind you it works better now I have fixed it than when it was new.
Its a bugger to fix as well as you need to remove the epoxy they put around the joins and redo the connections.