I know, that the cooling is better, but this means only "rare YLOD", not "no YLOD". As long as you have BGAs, there are solderjoints, which get faulty. I had PS2, PSP and DS with broken solderjoints at an BGA, all the BGAs had no IHS. And - big suprise - the Xb360 has the same problem without having an IHS IHS. Therefore it's absolutely crap, that the PS3 will have no YLOD because of the missing IHS.
With or without BGA station, you have to remove the IHS. If there is no IHS, it is easier.
And no, reballing is not the ony way to repair the YLOD, you can only use a reflow, if you do a good reflow. The problem is, that many people reflow their mainboard a heatgun, heat it up for a few minutes and that's it. This is a bad reflow, but not the only way to reflow a BGA.
One more thing. The IHS does not define the temperature alone. The fan-speed effects effects significantly more on the cooling than the IHS. If the heat transmission is worse because of the IHS, than the fan speed gets higher and the GPU-temperature is the same -> no effect on the temperature, only on the fan-speed. And the temperature is preset in the PS3, to hold the temperature at the same level, indipendent of the cooling situation.