Mines 2.5
This is what I've learned about mines after playing beta 2.5:
Mines are best used offensively. They cost so much you need them to blow things up - otherwise they are a waste of resources. The cost makes it appropriately expensive to mine jump-in spots but it's still annoying that you have no choice but to jump in a minefield even if you know it's there. There should be a way to prevent that.
Vasari mines are very powerful and have great fleet wrecking potential. Freshy deployed Vasari mines near your fleet that havent activated should be priority targets before they detonate and your fleet disappears.
Advent mines are amazingly easy to deploy but horribly ineffective. I had two full squadrons of mines detonate on a tight group of 35 cobalts and maybe one or two ships blew up. Both explosion radius and damage seem rather pathetic. I also mined around enemy caps and they didn't make an effort to shoot the mines before they started homing in on them. Advent mines need to do more damage to be useful for the cost.
I think all mines that detonate should damage all ships within blast radius, your own included. This would put their focus more on the defensive.
I would probably make mines a little cheaper and less offensive overall.