An observation - All THREE studies that are being sited were done by the same researcher team. This introduces the possiblity that researcher bias may have tainted the study. At very least, it indicates that they should really be considered as a single source, and not three seperate studies.

Second observation - Other researchers (don't remember exactly which studies, and don't have time to search, sorry) have reported that it is precisely because THC has such a long half life that withdrawl symptoms are so mild. A heavy smoker who suddenly quits will have quite a build up of THC in his system that takes a long time to burn off - a process that does not occur suddenly. This gives his body time to slowly adjust to the gradually decreasing levels of THC.