I use a 45 watt Weller 4033S heater (really big chisel tip) that fits in a screw in handle. The rated tip temperature is 1100F (yes, over 1000). It is not temperature regulated. I pre-tin the wires, then squeeze them in a vise until they just fit in the slots. Put some flux in the slot, put the wire in the slot, flux on top of the wire, a little solder on the iron, and I can solder a post in a second or two.

High temps like this are too much for the ESC only if you hold the iron on the post for too long. I know 1100F sounds like overkill, but the hotter the tip, the faster the heat gets into the joint and the less time the heat has to get down the post to the electronics. If done correctly, it ends up being less stress on the rest of the electronics. It is essential to use flux with this technique because that gives the instant heat transfer that lets this work. I've been soldering stuff for about 50 years and this works for me.

Pic, for reference: http://s92437987.onlinehome.us/ebayp...ight-3-rx8.jpg