I just finished reading “America’s Ruling Class — And the Perils of Revolution” on another thread. Fits nicely with your quote.
Dune examines a variety of classes: government, social, economic, political and religious.
Do you believe the series is comparable to Atlas Shrugged as political commentary? Furthur, is the series a source of insight into our current history?
I may take them up after all.
I would say "not so much" to the first question. It's there to some extent, especially in the later novels of the original series, but it's there mostly in a subtle way (the above quote from Heretics of Dune was a rare explicit moment in that regard). As to the second question, the Fremen and their rampage shows the Muslim militant mindset that we all know all too well by now. The Sisterhood is of course patterned after the Catholic Church, and is depicted in both a positive and negative light (one character says that "The Bene Gesserit are so close to what they should be, yet so far"). The spice itself is analogous to our dependence on oil.
The overarching theme though is one of freedom for humanity, freedom from any single dominant force controlling (or preventing) its growth.
By the way, a somewhat shorter work by Herbert exploring similar themes is the Voidship series, starting with Destination Void. It is more hard SF than Dune. I've only read the first two books but it helped me understand the Dune series better.