OSB has no internal voids, unlike plywood. Advantech is a premium OSB flooring that says if used with polyurethane adhesives during install provide superior floor strengths. Might be a benefit if you have heavy shop equipment.

OSB is used all the time for sub-floors. It is really cheap right now as well.

My only question would be if the OSB is smooth enough to accept vinyl. Isn't the usual procedure to use luan and then fill screw/nail holes and seams before laying the vinyl?

Mike

OSB, pressboard and luan plywood are not an acceptable substrates for ceramic tile according to the NTCA because of their tendendancy to swell when wet causing the tile to fail.

The Resilient Floor Covering Institute, a trade association that represents manufacturers of vinyl sheet-flooring and tiles, recommends plywood as an underlayment material and only accepts OSB as a subfloor material. This is because of the high potential for edge swelling of OSB which can be telegraphed through the flooring product. Many resilient flooring manufacturers will not guarantee their product over OSB.

The best substrate is "underlayment grade" plywood.