All I know is that I have one of the big Wellers, but after using one of the butane pencil torches, they heat up a localized area so much quicker that I don't have any issues now. I hardly every touch my weller now. And I ALWAYS flux the wire before I tin it. When soldering Deans, I usually use a small heat sink (that is, clamped on hemostats, between the plastic and the solder area) if necessary, to keep the plastic from beginining to soften. Just my $0.02

Dave