Xbox 360 Preventative Maintenance
One should also take into consideration that dust and overheating are not truly the cause of a RRoD error unless it's simply overheating. I've reballed plenty on consoles, as new as 2009, with no dust whatsoever in the system. I've also done tray cleaning and lubrication on consoles that were filled with thick layers of dust without ever red ringing.
Yellow Light of Death Repair
I can't believe people are actually getting results with this, heat gunning the RSX is at most going to allow for a poor reflow and possible warping at the corners of the chip without a proper board holder.
Also, at the temperatures required to reflow the solder, the thermal transfer compound between the RSX chip and it's heat spreader is going to be rendered much less effective.
As preventive maintenance, replace your power supply if it's the less efficient ZSSR539IA model with an APS-226 or 231 and clean then reapply the thermal paste. Once the YLoD occurs though, the system really needs to be reballed, reusing old solder and possibly shorting contacts under the chip with leftover flux is a bad idea.