I’ve had this laptop since June. I also added a 16GB DIMM as well as an HP EX 950 1 TB secondary drive. I love this laptop! It has been flawless. On silent mode, I literally cannot hear anything and it would be a dealbreaker if I did. Perhaps your fans were going out?
The "upgrade" section showed an empty second DIMM slot. Does that mean that they tested it with the RAM running in single-channel mode? I've seen crazy numbers about the FPS impact of running in dual-channel mode -- of course it depends on the game, but more than one person has said things like "20-60%", which is enormous.
I guess in a way it's Asus's fault, for soldering on one module and only selling it in 16 (single) or 32 (dual) configurations. I really don't consider it an apples-to-apples comparison, though, when you make charts where one machine is running at full potential, and the other is crippled for want of a single cheap, easy-to-install part.