I have and it works great!!
Never wanted to use the heatgunfix, so I tried the toothpicks for my 0102 error. hey worked for a month but then I got the errors again, opened up my 360 to see that the toothpicks became pressed in (dented?).
So they didn't put ny force on the clamps anymore.
I then read your post and decided to give it a try, but instead of using a card I used hard pieces of plastic (pieces of a CD jewelcase).
I placed them (2 stacked pieces of plastic per X) inside the centre of both the X's on the bottomplate.
Then tightend the 8 screws, the screws were almost too short after adding the plastic
This way the GPU and CPU are pressed firmly against the motherboard.
My 360 is up and running again for a week after applying this trick, I've been playing GRAW2 a lot and it's still going strong

Great stuff I'm really pleased that people are having some success with this. Lets hope all stays well.