I’m way late to this discussion but just to add my $.02—I find the Debugger to be extremely effective although it definitely does affect the signal enough that you’ve got to make your personal decision as to whether you can live with it or not. However you also need to define exactly what you are targeting. As the original poster discovered, line hiss resulting from cascading FX units, buffered bypasses, etc, has nothing to do with 60 cycle hum that the Debugger is all about.
Sorry to repeat what has already been covered but I just wanted to pay my props to this remarkable box. I am not 100% sure how I feel about the compromise it represents but I’m so damned impressed by how it is the only thing I’ve ever found that truly does the job when that neon Bud Lite sign is destroying your single coil sound.