I have come up with my own but very similar method of this after doing some research.
I too had limited success with the rrod, error 0102 which after xclamping through the chassis worked for a short while, maybe a week but with freezes, then after more fiddling turned into an e74.
Also tried the penny/rubber/xecutor rrod fix with no success.
One thing I did note is the motherboard is visibly warped at the rear near the fans, it seems to me to be because of the chassis, there is an indent point that the rear of the dvd screws into (approx. in the middle) which seems to be too high, only by a mm or so but enough to distort the middle of the board upward. You can see it easily with the fans removed. I took a hammer and adjusted this peg

Having read this white paper from manncorp
XBOX 360 rework station it would seem that even and controlled reflow is the best answer. As far as I can see using a hot air gun is so random, you cannot be sure of correct or even temp, nor can you heat both sides of the board at the same time. The possibility of error is high.
So heres what I did.
Prep work:
I removed the board from the chassis then using some blu tac covered the eject and controller sync buttons. Then using some old socks (adult size) used these to carefully cover the caps connectors etc, basically leaving the GPU, CPU and ram clear. The socks were stuck to the board using electrical tape and also to the underside of the board to cover the various connectors.
Then I took some blu tak and rolled it into several long thin sausages, about 5mm in diameter. Then applied this to the board basically between the components I wanted exposed and the electrical tape. Essentially making a gasket. I also did this on the back side of the board around the GPU, CPU and ram.
Then I took a large piece of alu tin foil and started at the edge of the board started to wrap the board but leaving it slack pressed the foil into the blu tak to seal it, (Thus no fabric or tape is directly exposed to heat source). Then wrapped it around the back and pressed it into the rear gasket.
Then using a small craft knife cut the foil in the middle of the gasket. Lastly I wrapped a few more layers of foil over the cap areas, edges etc, not using anything other than the distortion of the foil to hold it in place.
Cooking:
Using our domestic fan assisted electric oven I set the temp to 220-230C which again according to all ref should be sufficient to cause the solder to reflow.
To check I took some flat foil and but a lump of blu tak in the middle then took several lengths of solder and placed them in it (taking a short length and making it a small L shape was useful as it easily showed the points that the solder would soften or melt.
I then put this test piece in the oven to ensure it was hot enough and the fan airflow wasn't going to cause any problem. I then observed and timed how long it would take for the solder to melt. I also tested with solder that was already heated and cooled to check the effect was the same.
Basically we want to heat the gpu, cpu solder to reflow before excessive heat soak gets through the insulation and damages or melts anything else.
I found that approx 270 seconds (4 1/2 mins) was sufficient to melt my test pieces. (5 mins max).
So then I shoved in the prepared board, for the just under 5 mins at approx 230C.
At the end when I opened the oven there was a small amount of smoke from the electrical tape so I pulled the board out and left it to cool on the side. After about an hour I carefully removed all the insulation, blu tak etc and reassembled into the chassis using x clamp replacement method.
There is no visible damage to any components on the board, nothing has fallen off or moved, the solder on the underside of the board has become a more golden colour consistent with how it should when it has reached reflow temp.
(cooling mods are whisper max fans, xcm core cooler running at 5v and shroud mod which it had before failure anyway)
Connected it all up and the dam thing worked. Have now been running it on and off for 8 hours or so with GOW2 and not a freeze or glitch so far.
I have no expectation of it being a permanent fix if there is such a thing but as this is a spare box its nice to get a bit more life from it.
The main considerations of this fix is, protecting vulnerable components and using sufficient heat but not for too long.
First of all I would like to say that I love xbox360-big fan-, but this is so sad that ideas like this have to happen in order for the system to work again. Does M$ see this and if so what do they think of this? There must be a response from them about these ideas. This system has to be the cheapest quality made product in History ! I also had 3rrod 1 year ago and now I have 4 fans and 114db of noise. This is ridiculus. But ofcourse I will still use the system because it had good games.