SttC was absolutely an overpowered strat pre-nerf.  It needed a fix to bring it into balance.  Making it require 8 labs was not sufficient.

But I contend that the devs went too far in its adjustment.  Taxing it at fleet upkeep rates and vastly increasing the time it takes to mine has effectively killed this as a strategy in the game.  I find this unfortunate.  The ability certainly added a very different play style and flavor to Sins and now it's nothing more than a novelty that simply isn't used in any level of competitive match. 

I would suggest bringing the SttC tax penalty to half (or less) of the fleet upkeep rate.  Keep the longer time frame in place, it should be difficult and risky to strip a planet that is outside your controlled territory, but the pay off has to be worth it and it simply isnt right now.