Heh, there are many persusive techniques in that essay. Repetition, expert opinion, generalisation, atack on opponents, perhaps some exaggeration, appeal to justice. Probably more...
I agree that good teachers in the public sector need to be paid more, although most teachers I've come across are good teachers (I've had 2 teachers in 6 years of high school that I really didn't like - although I had more poor teachers in Primary school than that). I don't really agree with performance based pay, because it's difficult to gauge how good a teacher is just by the performance of their students. If you're teaching a bright group they'll get good test results and improve over the year. If you're teaching a weaker group well, some will improve, but some will give up entirely, overall the class won't perform as well and there's a limit to how much a teacher can actually do to change that situation. And the result would be a flight of good teachers out of the poorer performing schools that need them. I think that there is probably room for more decentralisation though, but the union is still pretty important for attracting attention to the cause and bargaining with the government.