I have not done direct comparisons between glass-insulator and ceramic-insulator fuses. I have listened extensively to the same system running through fuses and through breakers and have never noted a difference but haven't done ABX comparisons, which I think would be discounted by the folks who are chiding me, anyway....
I have a considerable concern about the use of magnetic circuit breakers because they have a built in inductor through which the power passes on its way to the outlets. The chance of that being an issue is small, though, because magnetic CBs are rarely if ever used in domestic wiring.
With respect to causality of perceived sonic differences with varying insulator materials, I'd be as much or more concerned about the internal construction of the circuit pathway and the materials used therin. So far as I know, there is no easy way, short of dissecting and bench-testing several brands of fuses, to know if the ONLY difference between the fuses was the insulating material. That point being made, even various brands of ceramic or glass fuses might have different innards. My suggestion would be to get as wide a variety of fuses as possible and test them and choose the one that sounds best. Pretty simple.
Now, as to the tone of my post. As I noted in a private email to cfb, I do have a wicked sense of humor. I have no intention of abandoning it but perhaps it will be easier to tolerate if you realize that (1) I am just as willing to turn that sense of humor on people in my own camp as on people in other camps and (2) I am not given to taking offense when people poke fun at me. I do, however, take offense when people tell me to shut up or, in cfb's case, to take my finger off the submit key.
Finally, my point in that post was that there exists a continuum of opinions about the sonic effects of various components, cables, tweaks, et alia. For example, in the current issue of $ensible Sound, one of the reviewers says that all amplifiers sound alike. Sheesh! Does he have any ears at all? On the other hand, a fellow opined to me the other day that hanging a picture in one's listening room that happened to be framed in metal would "render the sound utterly unlistenable." I reserve the right to sound both bemused and, yes, possibly condescending about such extreme opinions. As to the rest of us who fall somewhere in the middle, my position remains unchanged:
IF YOU PERCEIVE A DIFFERENCE IN THE SOUND, AND YOU LIKE THE DIFFERENCE THAT YOU PERCEIVE, AND YOU CAN AFFORD TO MAKE THE CHANGE, THEN DO IT.
And for goodness sake lighten up. We're supposed to be doing this because it is fun.
Willie