Can't speak for the Lechler mate but the Rustbuster and this one are safe http://www.refinishsystems.com/product/754-199/HBBody125LEpoxyPrimerKit
I've also had no luck with emails to rust buster.
As a new customer I thought I might have a response by now being a week later. I emailed them to ask about their epoxy 121 & the rust converter & recommendations on what to use for different jobs on my Range Rover Classic etc.