TechTool Pro costs less than Disk Warrior (in fact, there have been a couple of recent sales of TechTool Pro for $39.95).
Paying for upgrades is definitely the wise thing to do. Anything less is asking for trouble. In fact, there are instances where one must pay for the upgrade in order to use the new version with the new OS.
For me, Disk Utility has shortcomings, and Tech Tool Pro, a proven, solid utility, does so much more. And, it is so much easier to use it, with its eDrive feature.
Again, as I stated above, one key fact is being meticulous in taking care of one's machine. And, my analogy with that and taking care of a car is so, so accurate.
