Dreadnaughts and battleships usually make up my warfleets, and my support vessels are often battleships or battlecruisers, or at least whatever my highest ship tech is at the time. I don't usually make Dreadnaught-class support vessels, as I usually re-assign them to other various tasks.
However, I also make use of frigates quite often, in a role I had previously used escorts for (you heard me, escorts), the role of terror weapon. Using a combination of stealth armor, scattering armor, and ECM, the frigate has a total defense bonus of 110%. Add in ship training facilities (and fleet training facilities) and the end result is a ship that is almost impossible to hit for any but the most pious of races.
Now with two solar collectors, a solar sail, a master computer, and 6 quantum engines, there's not much that can be put on this ship, so I just slap on my highest level plague bomb. And it can hardly ever be hit, even by planetary defenses, and it only needs to hit a planet once to be effective, so even if weapons platforms or defensive fleets get in a few lucky shots, it still has a very good chance of infecting the planet below.
I can only imagine the look on an Emperor's face as he gets a report of a small group of frigates destroying his empire, and all those dreadnaughts and starbases can't do anything about it.
-Hotfoot
"Now, unleash the Terrors of the Shaderni."