We recently had our hardwood floors sanded and refinished by professionals with a clear water based polyurethane (a Bona product I think?). We chose the waterbased because of the time of year we were doing the refinishing (summer/high humidity) and they were having some issues with the oil based curing in a timely manner in some other houses they had done just before ours. Also, the VOC were a consideration as we were living in the basement while it was being done. We had 3 coats put down and we were relatively pleased with how it looked when done even though it wasn't quite as rich as the factory finish.
It's been about 18 months since it was finished and I am dissapointed by how many scratches there are in the floor from everyday wear and tear. We adopted a 2 year old retriever about 6 months ago and the wear has significantly accelerated. We got 9 years out of the factory finish (3 big dogs for most of it) but I think we are going to have to buff and coat here in another year or so. If I were to do it again I'd probably go with an oil based and just try to do it during a better time of year.
Also, if you are having it done, pay the extra for the dustless system. I was shocked that it actually was dustless and was able to cancel the cleaning lady we had scheduled to come wash down the walls, windows and other surfaces.
