Does a weave of cables really make a difference?

I have a mix of good quality cables -- speaker, AC, XLRs, USB, but they are a mix of brands. I would say they are all in the same quality/price range - $200-800.

Has anyone switched from a mix of brands to a weave of cables (my understanding of a weave is all one brand at the same quality/price level) and found it to be a big improvement? I would like to hear from people who have actually done this. 

I am quite happy with my current sound, but would make the change if others have found there to be an audible difference. One of the audio dealers here claims it will make a huge difference. 

I will add that I could easily hear an improvement with speaker and some slight improvement with the XLR's, but not so much with the AC cords. Also, I'd rather not just try  weave out (as much as that makes sense}, as changing all the cords would be a real pain.

Thanks in advance.