I'm sure you can guess, I have already posted a rant about these on the forum and why they are a bad idea
I don't want to ruin Phil's sale's so I will be fair
In summary, if you wanted to use one to diagnose the problem, then sure why not, it is going to help you point out whether the problem is with the +5v supply from your driver board, or something else on the cpu board.
But, it is masking the underlying problem and you have to remember that all the other boards in your backbox are also connected to the same +5v rail and thus if you have a failing +5v psu this could cause problems with other boards.
Additionally if you have mods running on the +12v rail (as many do) you will likely be over-driving the +12v rail by adding the cpu as well.
In summary, they do work, and could be useful for diagnoses, but I disagree with their use as an expected permanent fix