FWIW, and possibly unfortunately, I agree with your friend. The short moment when the door is open isn't sufficient to justify matching the satin nickle inside; and IMHO, metals within eyeball range should be at least of similar color. One sees (even if not consciously studies) the exterior lights and exterior knobs as a decor unit, and upon departing, the room's interior knobs (whether cabinet or several doors) are a different unit. I realize the SET of mix/match knobs looks strange while it's in your hand, but honestly, once installed, I don't think anyone ever stands at the door's edge in order to eyeball the interior and exterior knobs at the same time. I suspect you'd have to work hard to name any m/m sets in your present world, and yet there are likely to be many (especially on bathroom doors).

I just went through this while redoing two bathrooms. I started out with satin nickel on everything - plumbing, light and handles - but then realized that I much prefer ORB for lights and handles for my med stained QS oak mirror trim and cabs. I asked a designer friend if I was delusional for wanting to mix these on top of brass door knobs. Her reply was that if I was, she was, too, because she's designing a bathroom with exactly those finishes down to the brass door knobs. I paged through my stack of shelter mags and spotted a number of bathrooms and kitchens that mix it up with hardware finishes. It looks good because everything is in the same style. In other words, you can mix satin nickel with ORB as long as you don't combine a modern faucet in satin nickel with Old World cab handles in ORB. btw, pay attention to the ORB finishes of your choices because that finish isn't consistent from manufacturer to manufacturer. Some are a dark brown matte while others have a dark coppery color showing through where wear might occur. I think mixing different ORB finishes would be more noticeable than mixing ORB and satin nickel.

Matching is out as a style preference. Generally, one matches hardware as a device for toning down a design that has too much going on in it. If you have a normal kitchen that isn't making people's eyes bounce all over the place there's no need to do that. Since you're taking about vintage looks, I'm assuming you're talking about something like a black wrought iron for the chandelier, not glossy black enamel, right? That would look great with the antique pewter pulls. Like a black sweater looks good with antique pewter beads. Go for it! If you're talking more something like the one below, then I'm not so sure, and would wonder what the rest of the kitchen looks like.

Those items do not have to match, but they should correspond. And in this case I would not put ORB with reddish brown. If you're going to do two different metals that close to each other, they need to be different enough as to not look like you tried to match and failed. Either use the same metal or something strikingly different.