The design choice German destroyers could not avoid

Could Germany have improved its destroyers by acquiring British J-, K-, and L-class plans?

There were many ways to improve them, but the central issue was deciding whether they were destroyers or small cruisers rather than mixing the two concepts.

A 5.9-inch weapon is a good gun but belongs on a hull stable enough to use it properly. A destroyer fighting at high speed and closer range instead benefits from lighter guns, higher volume of fire, and twin mounts. The real design decision is whether to build a destroyer or a small cruiser, rather than an unhappy hybrid.