It was a bigger deal in the first builds where it was a tier 3 tech with no prereqs. In multiplayer its actually not that viable because teching up straight to it is expensive, plus you still need to spend a lot of money developing lots of planets if you used it to its main effect. You'd have to be playing a large game in the "eco" slot to make it work, as if you are on the front lines your neighbor who spent that money on military will kill your many unprotected planets without a challenge.

Was playing large game.  The other the closest ai to me was rebel also, so got no challenge from them.  Still had a good size fleet going because of the income of rapidly upgrading my planets.

sorry but TAR is the TEC rebels biggest weakness - you dont get the XP and when you encouter another player or AI with leveled capital ships its all over for you

I would not call it a weakness but a tradeoff. Yes you do lose XP, but it allows you to expand and get territory uncontested and allows your allies to get this XP with their capital ships.

Question, let's say you researched it and there a few Neutral Colony planets left on the map. How do you attack them? Or you all of a sudden can not? 

wait...vorazan, are you talking about the neutral planets that are actually owned by the militia?  You would only see them on a custom map, but if that's what you are talking about then no you can't take those planets (just like you can't take the pirate base once you research TAR)...

I usually get it in multiplayer games actually. It's really not that hard to rush in the eco slot at all, and I sometimes even rush it on the front line if I'm matched with someone I know will kill me in the starting battles. It basically makes you unkillable for most of the game while you take the center, and if your team has better luck than you did it allows you to come back with a vengeance.