Personally, I'm in the "stay with OEM stuff - including paint codes" camp. However, you do raise a good point about the interior washing out. I think that the flake in the GM paint would definitely accentuate the trim more than the piano or even sapphire blacks and it may really break up the dash/door panels and centre console nicely.

There's no way to know unless you try it; if you don't like it, you could always sand it off and repaint it.

I'd say it's at least worth a shot.