I ordered another mech, the
sigelei #23. I read somewhere that the switch design is a little different, similar but no spring in there. I can't find that info at the moment otherwise I would post a link. I will send the #20 back as soon as I get it and I should only be out a couple extra bucks, and that is if I have to pay return shipping. Not sure if I can just refuse the package and the vendor will accept that for a return/refund.
Its too bad because I love the look of the #20, but I would be thinking about that little switch spring constantly as I am
vaping on it. Normally I don't worry about stuff like this, but being an engineer I can see that very little thought was put into the design. They could have easily put in a beefier spring to reduce its temperature while current is passing through and no one would have had a problem. Instead they drilled out big holes in the sides to passively cool it.
To all who own the #20 or are thinking about buying one, just read the info around the web and decide for yourself. If it doesn't bother you, go for it or keep on using it. There's a good chance you wont ever have a problem, and its your money and your equipment so its your choice.