It was a nice read and thanks for sharing it. But frankly I have different opinions when it comes to identify how experienced domain brokers are.
First, the biggest problem with the broker experience part is that almost every domain broker has few selected rules and old-school criteria to accept certain domain names only for selling (as mentioned in the original article). Another problem is that all brokers do not pay attention to "what's the next big thing coming", like future tech names and etc. I know these names may not fit to the 3% of what these brokers would love to sell, but when the time comes, these tech domains (and other niche domains) surely hold potential to prove their premium'ness in the future. At least that's what I believe and confident about.
Secondly, hiring a broker is not possible as long as you don't own a premium domain; that's right, a one-word .com or, 2,3,4 Ls and Ns. I know the majority of domainers (not all though) do not own such premium names but I am also sure there are many domainers who have gems in their portfolios which they want to pitch to the right end user, and for that they find it necessary to hire a broker to start and represent things professionally.
Lastly, domain brokers only accept domains with huge sale prices, i.e. so that they can earn big commissions. Nothing wrong with that but I think it limits their services, experience and potential opportunities these other non-premium domains can offer.
These are just my 2 cents and with no offense meant to anyone and with utmost respect to all.