I've had an Acura and Nissan with manual transmissions. Both shifted much smoother with redline. BUT, I did not compare with the Nissan OEM. I'd compare them both by running about a month each. Molecule taught me that MTF's need to be run a little to allow their "chemistries" to become fully effective in a manual transmission.
In other words, you can't just change fluids and compare the shifting immediately. Give the new fluid a few miles to work its magic. He was correct.