This is where you really need to trust the judgement of your floor man. I hope you've seen his work in old homes and verified his references. I think the modern water based polyurethanes are superior to the oil, but that's just me.

I re-posted my query on the flooring site, and added some pics.
This flooring guy is one of my heros since he rescued someone I know from a disreputable contractor, and did a beautiful job. The contractor tore out a floor in their condo and left them in a homeless situation for three months, because he used such flimsy materials that the floor was unsafe to walk on. The sanding, staining and first coat of poly was done today. After the sanding, it looked great and I wished I had done all the floors, but after the poly it didn't look all that much different from before. I could only see it partially of course, since it's roped off. Well, at least I bought the floor some more time. I hope I look that good at 109, and someone appreciates me!