First of all, bear in mind that these comments apply to the 1.72 edition of STmod... I've never played 1.75 and you may have addressed some of these concerns already in that Version
I would like to see my custom warhead pics used for the warheads, seeing as you do have multiple damage types for your warheads and you can't tell them apart visually on a mine design.
The pics are in the Imagemod.
Also, while this might be a major design decision that you don't want to implement, I personally think impulse-only ships should be slower than they are in STmod - I know having warp ships travel 1000 times faster than impulse ships is impossible in SE4, but 3 times times faster might be doable instead of the current ~1.5 times faster? (Maybe warp cores could be scale mounted, too?)
I also think the bussard collectors and ramscoops provide WAY too many supplies for their tiny size and low tech requirements - currently it's possible to make starships practically self-sustaining without consuming any noticeable amount of tonnage, rendering supply depots useless... or did you intend that to be the case, given that starships were often sent on "five-year missions"?