For me the prediction failed - we started around 6th and played ca twice every 3 weeks and with roleplay & story bonuses I gave out around 50% more XP than standard (though this varied a lot), but the group hit a bad patch around 12th level where PCs were dying all the time, often un-ressable. They spent at least a year without significant level advancement - a PC who had retired at 13th when his player left in May 2003 after a year's play from 6th, and was the highest level then, was probably still higher level than the in-play PCs a year later in May 2004!
So the projected advancement rate doesn't take account of the effects of PC death, especially in the killer levels around 10-13.
So the projected advancement rate doesn't take account of the effects of PC death, especially in the killer levels around 10-13.