I'll chime right in and say that this software does have a lot of work in front of it but I want to earnestly encourage the developers to keep it going in spite of some of the dross feedback on VT. For all who've used this software here's my considered advice based on 10 years as a computer service professional. Do not run any defrag utility on any drive that hasn't been cleared by one or more of the better directory repair utilities; I myself start with DiskWarrior and then follow up with NDD because I know that even SpeedDisk has the potential to trash a hard drive if NDD isn't completely happy with it. Each directory repair utility must be run multiple times until it reports that no errors were found. Hopefully iDefrag will grow smart enough that it can deal with directories that have only had DW run on them because there will come a time (in March, perhaps) when NUM will not run on OSX any more. Hopefully by then iDefrag will be mature enough to take up the torch because TechTool is way too painfully slow to use on a regular basis. As for the debate about whether defragging is necessary these days I can say with much experience that while most smaller files resist fragmentation under HFS+, it still occurs and will still slow things down. Reduction of the number of extents by defragmenting is the only way around this.