This is good news! I guess I've been wrong all this time in assuming that even low TC gives warships a detection boost.
Just now I stalked and entered a convoy, making my moves at 4x or 8x, and I noticed nothing unusual in the destroyer detection. I slunk away (80m depth, silent running) at 16x and they didn't pounce more than at 1x. Subjectively, it seems fine here.
