Our colors. The very fact Boston threw a hissy-fit over that makes me want to use them even more.
Anyway, similar color schemes is hardly unheard of. Toronto/Tampa Bay, Edmonton/Islanders, Montreal/Washington, Chicago/New Jersey/Ottawa, Rangers/Columbus...and that's just in this league.
I actually liked the vegas gold for a while and didn't mind the shift...but it doesn't work with the new materials, it looks beige on RBK's uniforms instead of the shiny gold it was supposed to be when the color was introduced. I don't see the team shifting color schemes any time soon, but that's my view of it. If the Penguins go straight-up retro next year then I wouldn't be surprised to see the exact design promoted to primary in a couple years with the vegas gold taking over for the regular gold...if the Penguins go with an updated rendition with the vegas gold coloration then that's our next set of jerseys within 2 years without a doubt.
Either way, this fits into the time frame that I've been puking out for the better part of a decade - three alternate life-cycles before the primaries change, milk the vintage stuff as long as they can before they can relent and go with the one that everyone wants.