Alain:
As far as I can tell, rebuilding the disk directory with DiskWarrior is not the same as starting as a single user and peforming a fsck -fy and reboot or starting in "safe" mode which does something similar. Again, my experience is that DiskWarrior has been able to fix problems that these procedures did not fix. In one, rather memorbale case, it took 14 hours, but DiskWarrior successfully retrieved a directory that every other utility declared to be damaged beyond repair. In another case. after I installed Altiverb 6, Logic could not see it and kept issuing error messages to the effect that Altiverb 5 was missing. No other procedure fised this, but, after rebuilding the directory with DiskWarrior, Logic immediately found and validated Altiverb 6. I've had many similar experiences. Do as you wish, but I would not want to be without DiskWarrior. (And, no, I am not an employee of Alsoft.)