I watched a youtube review of the Harbor freight sharpener and it was well reviewed for what it was. That said, I would not take my Forest blades and try to sharpen them blades on the Harbor Freight sharpener. In the review, the guy was sharpening rather simple and inexpensive blades that he was using for cuts on wood that I would consider rough cuts.
Unsure about the "payback" time with cost versus time.
https://www.harborfreight.com/120-vo...ner-96687.html
Again, do not use this on your "fancy" saw blades. Your blades that cost $7 each, perhaps. Things like Framing blades.