Be careful about believing information that comes from a company that sells VO conversions. It is actually advertisement and in my experience often incorrect and always provided with the primary intent of selling you product. At the very least check other info sources to see if any of the info presented is contradictory to more recent research.

In this particular case much of the information IS  very outdated.

For a comprehensive website with out the bias always included in vendor website try looking at:
http://voconversionbasics.websitetoolbox.com/

Lots of tutorials and links to good (vetted) info available from other forums/websites.

At the very least be very skeptical of information which may induce you to buy from a vendor provided only on that vendors website.
There are a lot of very unethical VO kit/component vendors and even more that simply do not have enough experience to be designing and developing components.
Most often they simply do not do adequate testing before selling a product. This means that customers are the actual test program.