Obligatory "It's not the size, it's how you use it."
More directly, not really, no. I use size 5-6 at TL1-2, but past that I use size 4, since at TL3ish that's enough for a STR-4 warhead, ~66% CTH against 10km/s targets, speed in the 18,000-24,000km/s range, and a decent maximum range. Smaller missiles means smaller launchers and more missiles in the magazines, which means larger salvos and/or better combat endurance; a ship that gets a few STR-4/9/16 hits per salvo is more valuable than one which has all of its STR-9/16/25 missiles shot down; a ship which can get some weaker hits every salvo for a lengthy battle is worth more than one which
might get one or two stronger hits per salvo if they're lucky, and can't fight for as long without running dry. Adjust variables to suit roles.
It also makes them cheaper and faster to produce, if you're in dire straits.
Detectability doesn't mean much for your missiles; the AI doesn't exploit potential tech advantages by figuring out your range from metaknowledge and hovering it, and you're not going to get missiles small enough to avoid
all anti-missile fire unless you build AMMs that are basically just ECM pods.
But yeah. As with many other things in Aurora, missile design has several core principles to keep in mind for optimizing (the square-warhead rule, knowing to look for the peak value from agility, &c) but still has plenty of room for personalization.