True, true...
Yet it certainly looks like the Klingon enemies are very large in physical size, and rather clumsy in maneuvers, in both "Yesterday's Enterprise" and "Rascals" where the same footage is used. The size effect was very intentional, and IMHO shouldn't be lightly ignored.
Also, to nitpick, the big ships of the alternate timeline in "Y'sE" are called the K'Vort class, but they are established as the B'Rel class in our timeline in "Rascals"...
Personally, I don't find it difficult to believe in two or even three sizes of winged Klingon vessels. It is quite possible that this winged structure is required for certain types of atmospheric fighting that the Klingons do, and thus several very similar types are built, to varying sizes. Witness for example the landing craft and landing ships of WWII: very similar hull forms, very distinct from all other warships, but over a range of sizes from a small half-platoon-sized boat to an oceangoing transport vessel.
And that really is something I would like to see more in Trek. The alien opponents should have distinct styles of fighting, reflected by their vessels. Klingons have these winged things that look suitably "antiquated" to match their bladed weapons. They may actually be handicapped in space battle as the result, but that's their style.
Similarly, Cardassian warships may be optimized for planetary intimidation and conquest, with bloated underbellies full of invasion shuttlecraft, and with a single mostly down-facing main gun array intended to bombard planetary resistance. They may be very good at what they do, better perhaps even than their Federation counterparts, but they suck at space combat as the result.
Timo Saloniemi