Oh, no, quite a bit larger than that. At least one of the techs is +25% all by itself, plus there's a miniaturization superproject and a miniaturization random event. I seem to remember that the final total is close to +100%, which doubles the size of the hulls.
Sadly, part of the size of most components comes from the hull it's placed in, meaning that some things get larger when you put them in a larger hull, so you really don't get all of your miniaturization bonus. The later weapons/defenses/engines/etc tend to scale less, so miniaturization benefits them more than the early versions.