I have no qualms about mixing manufacturers for cables. For me affordability has to be taken into account, I will buy "bang for the buck".....but the sound has to be there. I personally mix cables, based on what each company does well and sounds terrific.
I use Morrow Audio for analog RCA and XLR cables, Supra Cables for digital cables (USB, ethernet, HDMI/I2S), Audioquest Vodka for HDMI/I2S, Anticables for speaker cables, Cullen Cables for C7 power cables, and Pangea Cardas copper power cords.
I will soon be replacing the power cables (not sure what with yet, suggestions welcome), and rolling in some Zavfino interconnects for comparison.