Where is your data that shows this "1%" variance? Seems odd that these audiophile fuses require you to go up a size just so they won’t blow (even odder still when they are touted as 1% tolerance!).
Those "standard cheap steel" fuses do not exist as fuse elements are not steel. Besides, take a look at the data sheets of Littelfuse, for example, and tell me where I can find the same for the boutique brands. Also, if standard fuses have a 15% out of tolerance, then how can Littelfuse make fuses with 4 ratings between 1 and 1.5 amps? (1.00, 1.20, 1.25, 1.50).
I’ll never argue about what you do or do not hear, but don’t throw the technical stuff at me as justification. Going up a fuse size because you want to save your $100 fuse investment puts at risk your many times more expensive equipment. What is protecting what?