As I originally stated, the clear trend is that there is an extreme lack of cruiser-level ships and an extreme glut of certain capitals. There are also a number of ships that are extraordinarily rare to find.
Since my original post I've begun collecting those rarer ships. I'll go through what I've found:
Capitals:
Paragon - plentiful (I have 4 with two more for sale???)
Onslaught - amazingly plentiful (literally everywhere)
Odyssey - plentiful (I have 4, they seem to switch off with Paragons at the Tri-Tach place)
Conquests - n/a
Astral - n/a
Atlas - usually a couple in the Ludd system (which makes sense)
Prometheus - n/a (I might have seen one early in my game, but not again)
Cruisers:
Apogee - one, which I fly solo
(reasonably fair, considering how powerful it is)
Aurora - two, one which was captured
Dominator - maybe 3 ever (surprisingly rare for and old and common design)
Doom - n/a
Eagle - 4 (surprisingly rare given how many the pirates usually have)
Falcon - very common
Heron - nonexistent outside of Sindrian space, in which there are stupid amounts
Venture - a few are around, but typically on non military locations
Destroyers and frigs are fairly balanced in rarity. I've found a number of Medusas at the Tri-Tach place, as well as a couple phase frigates and one Hyperion.
As for fighters, they are really rare everywhere, less common than some of the bread-and-butter pirate frigs.
Anyways, the point of listing out all this is twofold: to compare it with what others have seen, and to show how the heavier classes are really imbalanced. It seems that the smaller ships follow a fairly reasonable rarity level that matches their tier/strength, while cruisers are extremely lacking on all fronts, and capitals are heavily weighted towards a few which are extremely common, and the others basically don't exist.
