I've seen several threads mentioning this but i can seem to find what it is if anyone could help that would be much appreciated.

Is it the one that says large ships award half of their value if they lose shield tokens and take damage equal to half of its starting shield and hull values?

You'd better make darn sure you use Chewbacca-crew before the end of the game as that two point swing could be huge. Hull and Shield upgrades just boost the starting numbers so you still get screwed but if you can regain shields or discard damage cards, instead of starting with more shield tokens or being able to hold more damage cards, you're golden.

So am I correct in my thinking that this is only really relevant in large tournaments in which there could well be several players with the same win/loss numbers, or if my matches often go to time? I really only play store tournaments with, say, 12 people at most, and if I table all of my opponents I still win, right? That's a pretty big "if" in my case but just want to make sure I understand.

That's a pretty big "if" in my case but just want to make sure I understand.

To a point yes. It's mostly going to only have an effect when either you have matches to to time, or when there's a number of people with the same record.

So am I correct in my thinking that this is only really relevant in large tournaments in which there could well be several players with the same win/loss numbers, or if my matches often go to time? I really only play store tournaments with, say, 12 people at most, and if I table all of my opponents I still win, right? That's a pretty big "if" in my case but just want to make sure I understand.

The relevance has a couple of faces:

1. In a close game that "goes to time" this rule may turn the game's winner around. Previously, a 50 point Falcon that can take one more damage card would handedly defeat Wedge but now that the Falcon has awarded 25 points Wedge will win!

2. MoV is likely to be a lot tighter. When used to determine tie breakers this will make a difference.

Now if you just table everyone you meet then this isn't going to mean much to you.