Yes. This is what I changed:
Destroyer (Att:5, Def:3, Spd:3, Rng:1, HP:12, Cost:150)
Cruiser (Att:5, Def:4, Spd:2, Rng:3, HP:16, Cost:180)
I left the Sensor Range at 3 and had them both use the same ship model (because I didn't know any better). The AIs, particularly the Drengin, were building Cruisers like crazy.
I made the change because I wanted a military ship with a cost between 150 and 200. I picked Destroyer and Cruiser for class descriptors following your line of reasoning about traditional ship sizes (the "Frigate" discrepancy never occurred to me.
I don't know if the AIs chose Cruisers instead of Destroyers because they hadn't researched the necessary tech (I had the game set to stupid, since I was just testing modifications and ended up giving a lot of tech to my allies), or because they did a cost-benefit analysis and decided that they'd sell the Destroyers to Canada and keep the Cruisers as the better ship. At any rate, the AIs will usually pump out the the same ungodly number of Battle Cruisers, so maybe the modification was just fine. HTH
End transmission.
~SDC~