I bought my tubing notcher at Steve's Wholesale, a local chain comparable to Harbor Freight. It looks identical to the HF model. The notches are usually about 1/16" to 1/8" off-center. I really need to shim it back to center, but it's been a while since I built a cage. To me, having a perfect tubing notcher doesn't matter so much because you end up doing so much trial and error until the pieces fit. Cut everything long and trim it all to fit. Instead of spending the money on a high-end tubing notcher, buy a cheap one and spend the extra money on a second and third grinder and a 4' plug strip. Put a cutting wheel on one, a flap wheel on the second, and a grinding wheel on the third. You'll be using them all, and having them all plugged in at hand along with your chop saw and tubing notcher is gold. Also plan on burning through some hole saws.
Edit: That Woodward Fab looks identical to the Harbor Freight. If they don't say it was made in the USA, and you can't even tell that it wasn't made in the same factory, why pay twice as much?