@nt, Well I'm certainly not going to go crazy testing it every 15 minutes for IR. In my case as I explained early on in this thread I'm a programmer. This means I have windows open and I flip between different spaces all the time. At BestBuy I put a piece of tape on one of the LG rMBPs to see if it was swapped out. The unit runs from 10am til 9pm most days. Before I ordered mine I came in and ran it as if I were doing my work. I setup some spaces (****** off the BestBuy apple guy but so what). I opened some windows in various spaces and I tried to get the machine real hot. I had 6 term windows doing yes > /dev/null.
While that was going on I flipped back and forth, moving windows a little as I normally do. I then brought up safari and watched an 8 minute youtube vid while I moved some more windows. The fans were definitely on and the unit warm to the touch but just barely.
I went in and out of mission control, back and forth to different spaces and ONLY IF I set the base gray background could I see a little IR. Moments later when a window covered that area it was gone. If I set any kind of a textured background I couldn't really see the IR. Now this machine was several months old. I think it was this test that finally got me to place the order.
I'm at a doctors appointment now on my older MBP because my new one is home sycning everything and the kitchen sync from Dropbox and a few other places. I'm going to keep my eye on so I can use the 14 day period if needed but no... I'm not going to go insane and check it every few minutes. I'm going to use it like I plan to use it and see if I notice anything. If I do and it is an irritation but not bad then I'll probably live with it. If I do and it is bad then I'll return it. If no then I'm good to go.
I will tell you this... the thin lightweight design makes my 2010 MBP feel clunky! I'll keep you all posted but so far it looks nice and feels nice.