The actual mileage isn't very significant. If a sprayed chain lasts 8000 miles (seems low) and a Scottoiled chain lasts double, a small financial advantage would accrue at 24,000 miles instead of 30,000. Most of us would have sold the bike before then!

It's gotta be your choice. My main point is that the financial argument for a Scottoiler is weak. If you have other reasons, then fine.