By "piece" I'm assuming that Kevin means the Spyder2 colorimeter and not my guide (as he did not read my guide).
FWIW I agree with Kevin: The Spyder2 doesn't get most things right. Which is why I don't recommend it in my guide. I don't know any professional calibrators that recommend it.
P.S. I've now added Part 8: Advanced Colour Management (Primaries & Secondaries)
to the guide which makes the thing complete in my eyes. I will of course continue to tweak the entire guide here and there when questions arise to make sure it's easy to follow.