I have both Disk Warrior and TTP8. They do somewhat different things. TTP8 has a wider range of tests - memory, bad blocks, etc. Plus it has a way to undelete items that have been thrown away in the trash can. DW is a super tool and that really helps keep the Mac running well with its directory rebuilds. So a more comprehensive solution is to get both. If I had to only have one, I would have DW.