Lol, soldering isn't an onerous chore by any means, but to call it "fun"? Me thinks you've been inhaling the flux fumes a little too much lately. Almost like saying "it's fun to cut my toenails".
Anyway, 40W works, but I found you have to let that iron heat up quite a bit or the solder takes too long to melt because of the ESC heatsinking. A 60W iron gets the job done quicker while heating the whole ESC less because you don't need to apply it as long to get the job done. And you can always turn down the power of a 60W to a lower value (like 20-40w) for smaller jobs.