"Can one stain 'New' Red Oak to match 'Old' Red Oak?" This is tuff to do. When we do a repair in an old Vancouver Home I often use some Shellac first and then top coat with Polyurethane. The shellac gives me the aged look or yellowing and the two seam to work well together. Some times we tint the top coat a little. Judgement calls since sunlight and time will yellow the top coat so making it look right now might make it look wrong in a year.....

We have white oak kitchen cabinets with a very light stain. Our house was originally built with white oak floors, which we thought were red oak. We had to replace quite a few boards and we used red oak so now we have a red and white oak floor (definitely by accident). I'm with you on the white oak being nicer. Despite the efforts of our floor refinisher, the red oak still has a pinkish cast to it. In order to make the white and red oaks really blend, we would have had to go with darker stain on the floor, which we didn't want. Have you checked local cabinet makers for prices for white oak cabinets. We found that some could only get red oak and others could only get white oak. The guy who could only get white oak wasn't any more expensive than the guy who could only get red oak.

If you like your current colour then go ahead and put down a new version of it. If you want something different then I would go lighter. I love the look of red oak in the 'buff'. It is a pretty wheat/sand coloured wood. So long as you work with a high-end water based polyurethane that does NOT yellow, you will have a very pretty 'pale wood' floor without much effort. Your existing finish appears to be oil based (or oil modified) which makes the floor yellow. The strong gold tones in your wood right now = the finish. Did your refinisher apply a coat of FINISH over your colour samples? If they did NOT....then you are picking BLIND. And I mean screaming and crying and tearing your hair because your beautiful gray floors turned to a muddy orange mess. Not good. Do you see the pale colour of the raw wood? You can keep that colour (very close to it) with 3 coats of water based polyurethane like Bona Traffic HD. Keep the gloss level a snick on the low side (satin is a nice low-gloss option) and you keep that pretty 'swedish blonde' look.

Another reason not to mix custom stains. It doesn't take much to make the incorrect mix. Samples are measured with spoons, then you have to figure out the ratio for the actual project. It becomes more difficult when you need to do touch ups or spot fixes, which will most likely result in a entire floor refinish. Make things easy for yourself and stick to standard colors.