In theory the site-finished hardwood will have a slight edge on "water resistance" than factory finished. As Handy Mac points out, the finish will coat the entire floor in a single SHEET of finish. Now...that isn't to say it will be SUPER water resistant. It won't be. Most wood will have issues with large amounts of water allowed to sit on the floor. But the worry you have - water getting between the planks - is greatly reduced with a site-finish...again it is a large SHEET of finish that spans the boards = a thin layer of plastic = a little bit more water resistant than factory finished. Again...these numbers and 'time frames' are very similar. But there *should be a slight advantage for the site finished. That's why we require our cork floors in kitchens be site finished after installation - the polyurethane spans the joints making the floor resistant to surface spills (many hours of protection because cork itself doesn't care...but the fibre board in the middle does).

I have pre-finished hardwood in my kitchen (and entire house) that was installed about 18 months ago. So far there are no issues and no regrets. I just wipe up spills, go over the area with a damp cloth and then dry. Knowing my husband, I’m sure some stray ice cubes have melted, but they’ve left no evidence. I vacuum weekly or as needed, and use a bona mop about monthly. One thing I did do was buy new vacuum with a special soft brush designed for hardwood. The “hardwood setting” on my previous vacuum simply lifted the brush so it wouldn’t scratch the floors, but I felt like all I was doing was blowing around dirt and certainly not getting into crevices. There are pros and cons to all flooring, but one of the advantages with the pre finished is the strong seal that reportedly makes them somewhat more resistant to staining or discoloration. Prior to the hardwood I had tile for 23 years; sometimes it was really hard on my then much younger legs and back.

Ok...first things first. Janka hardness ratings only apply to solid hardwood. Engineered planks do not work with Janka because the plied layers underneath are often 'soft woods'. Considering Janka measures how much force it takes to imbed a metal ball into the wood, it isn't possible to offer Janka scores for engineered. They just don't compute. The next thing I'm going to point out is the oddity of trying to match the ENTIRE HOUSE to a single room of existing hardwood. You have a small amount of hardwood that is dictating the rest of the house. It's not impossible but it is HIGHLY unusual. In other words, you are trying to put down more than a thousand square feet of flooring by trying to match 150 - 250sf of dining room (I don't know the size of your dining room so I'm only guessing here). That's a little like putting the cart before the horse. Usually we see this the other way around. Usually we have a house full of hardwood (big amount) but the bedrooms have carpet (small amount). The homeowners then agonize over getting a match for the smaller area. That is normal. As for your price range that you are looking at, they are too low and a little thin. The gold standard is 3/4" thickness (solid or engineered). An engineered product with 3mm or more of wear layer is the base level. The thicker the wear layer the more times a floor can be refinished. The Gold standard is 6mm wear layer (usually in the $10/sf range). If you are having a hard time finding floors that you like, you might want to think about replacing the dining room at the same time. This takes away all the pressure to work with low-grade hardwoods just to get a match to a small amount of hardwood. Solid or engineered should be more than what you are looking at for price. Prefinished wood flooring should be in the $7/sf just to start and they go up from there.

^^^G & S is on it! The ONE who says 'I can do it' is willing to do it. The other TWO who say, it splinters do NOT want to do it. Let the guy who knows and WANTS to do it, do it. Be prepared...AO finishes double the cost of the labour. If a sand/refinish costs $5/sf for a regular floor, then you can bet it is coming to more than $7/sf for AO.