You might want to leave the Advent (unless you are hardcore) as the Vasari and TEC are fighting for the top spot now.

Yes. And TEC or Vasari are multiplayer top dogs, but it's still the case that if you leave an Advent alone too long, they're going to win.

They have attempted and it helped. A little. The phase missiles from the Vasari are just murder on a shield based race.

The Advent have always been annoying whores.  They make good targets for my AC's and phase missiles.

Again the Vasari were the least chosen race once apon of time with Phase Missiles behaving exactly as they do now. Its a huge advantage they have but it doesn't explain why the Vasari are so strong now. I think there are better ways to make the Advent more competitive without directly changing them.

Further, I advise that the Devs add custom map sharing to Sins of a Solar Empire: Rebellion.

I fully agree, all I'm saying is that phase missiles directly weren't the thing that put the Vasari over the top in the last few patches. Which to me means that the balance problem can be fixed without touching them. In fact now that the TEC is actually pretty good it seems that logical thing to do is just to buff some of the widely considered subpar Advent abilities to make them more competitive.

Granted, nerfing phase missiles would also help the Advent relative to the others as it affects them so much, but I feel this is the lazy solution to the problem, and could easily swing to far the other way.

Further, I advise that the Devs add custom map sharing to Sins of a Solar Empire: Rebellion.

Phase missiles don't automatically bypass the shields.  It's an ability that has to be researched in increments of a 5% increased chance of bypassing the shields.  After the first increment is done, 95% of all phase missiles will hit the shields.  After the second increment, it's 90%.  Even at the highest level of research (military tree level 5), 70% of all phase missiles hit the shields.

If phase missiles get nerfed, then you've just nerfed the Vasari and changed the game balance to where 90% of all players will want to play TEC.  Perhaps Advent needs a small buff to Illuminators and/or more Hull points and/or more Armor research and at lower military levels.  The Advent armor research is up at military level 6-7.  Maybe they should give Advent an armor research at level 2, and lower the second tier of armor research to level 4 or 5.