The problem with engine techs is that, if the opposing fleet stays in some kind of formation, the GSD will over-extend, leaving its escort behind and jumping right in the thick of it. It's easy to forget that the GSD is a small and can't tank damage like its larger cousin. This usually results in him being a one-hit wonder. He'll wreck shop for a turn or two, then crumble like the glass cannon he is.
Fleet positioning is key to discourage him pouncing on his terms.