Mike,
This topic comes up from time to time in this forum. I have seen comments boths ways (No problem and Don't do it). Personally, I installed Mercier prefinshed antiques Red Oak throught our Kitchen and Dining room about 1.5 yrs ago. We absolutely love it. Except for a couple of dings here and there (dropping a jar or similar object slightly dents the wood). I would do it again in a heartbeat. We have received numerous comments on how warm it makes the kitchen feel. We went with the wider boards, I think it was 3.25 if I remember right. When you get down to it, it's a personal choice. Do you have small kids, pets, etc... a lot of stuff comes into play. But like I said... We would definitely make the exact same choice all over again. As far as a sealer goes... There is a fellow named "Henry in MI" on this forum that really seems to know his stuff about wood. He would be better to answer that portion of your question. Good Luck! Mike