Yes, changing fuses can have a profound effect, for better (and worse). However, I am unaware of anyone claiming the purples amount to an other type of equipment upgrade (unlike the effects of a better QSA fuse). In my system, I've found the purple is a mixed bag: greater clarity and enhanced bass over the orange, while making the system pleasantly or politely warm. I like a bit of warmth, but not lulled to sleep.
OTOH, I've found the purple's warmth effect is overcome when AM Ultimate Premier fuse(s) is included. Depending on placement, one or two of the latter leave the purple's clarity in the dust, while at the same time stripping virtually all of its warmth and rendering the perspective stark and forward, something I don't favor. In addition, one of my two AM's, placed in a P15 regenerator, renders the system literally pitch elevated, as if, for example, the bottom half octave of a piano or baritone's voice were cut of and everything adjusted upward (frequency).