Think of mines primarily as area-denial weapons -- just like real-world minefields, which are used to cost an opponent time (either needing to go around them, or bring up engineers with demolition charges or mine rollers or the like).  By themselves, they should cause few losses.  Use them to cover areas not covered by your other defenses (such as beyond the range of your starbase's weapons), or to make long-range defenses (hangar bays, for instance) harder to approach, or for the occasional surprise (like mining your end of a wormhole).

The Vasari's gravity mines are a nasty trick.  Might be useful for shutting down somebody's attempt at retreat, if for some reason you have a Ruiner ready.

That's a good point leejaywu , thank you for that

Can't comment on beta stuff, but oddly enough, I find that TEC uses mines less than Advent or Vasari...  Hmm

Glad to know I am not crazy! After my encounter with 31 Advent Seeker Vessel, I was wondering if I might have played just a bit too much Sins. Good to know its not me. But DAMN!!!, 73 scouts, thats just priceless.

Do you have screenshots of this?

Mines: The AI does not use mines that often, I mostly see SMALL Vasari/TEC minefields and even less Advent.

true... but thats why we have scouts... so we can see whats really there.... sure, it means more micro, but you are about to go attack said planet anyway so you should be paying attention... on the other hand, talking about your own defenses... you should know what planets have what defenses

honestly, though, mines should be scaled down in that structure ticks thingo, enough to let you know how many you have, but.... if you have 150 mines, then...