This hardware is interesting, but let me share my experience and point of view of hardware diagnostics. I work for a bay area engineering firm, and we have many workstations, laptops, and servers. First of all, to be able to troubleshoot PC issues, you have to have some experience under you belt. With PC's now'a days, its a lot simpler to troubleshoot a system. We dont live in the old days of many jumper settings, configuring boot files, etc.
Get at least 2 years of warranty on your laptop. And resolve any issues under warranty. If the system fails after the warranty period (most of the time its just the hard drive--and thats easy, the thing usually makes wierd noises when it fails) then just replace it. Any serious issues (outside of OS re-install or hard drive replacement) is going to be too costly to replace anyways. The system is over 2yrs old, move on and get a new one.
Desktops are a little different, because there are more individual components in most desktops. The desktop device I would think is more beneficial in this area. But some of the same rules apply to the laptop scenario I mentioned above. Most parts + time is going to outwiegh the cost than just replacing the system in most cases.
Just my 2 cents from my experience.