Yes, here we go again. My 12-year-old son has run a list of 3 Onyx/TIE-D/TB ships against numerous lists with only small ships (in real life and Vassal), and in each case, it's been a quick and easy massacre.
I just don't see any way that list doesn't win unless the opponent has at least one large ship, and I wonder if even that's enough. If, for instance, you're running a large ship and mini-swarm, the Defenders obliterate the swarm in a turn or two (with likely no loss of ships), then go after your big ship, 3 vs. 1.
With small ships against that list, you can't fly anywhere near asteroids or the board edge. Where, exactly does that leave to fly? Yes, you can have debris fields, but then you risk a crit and get a stress, which makes you child's play for the tractor beams next turn.
Arc dodgers? The Defenders can easily spread arcs, and they've each got a tractor beam. And, again, maneuver is severely limited near asteroids (if the Defender player is smart, they'll only take asteroids), debris fields and board edges.
I was stunned at how quickly my son destroyed my all-small-ship list. I'm a solid player who's done well in many tournaments, and couldn't believe what I was seeing. The exact same scenario has played out every time, no matter what the other small ships were.
I'd be interested in hearing how anyone with an all-small-ship list has fared against this Defender list, or strategies that have worked in actual play (vs. theoretical).