UPDATED TO 1.8.1/Mercenaries
The Full Change Log can be found in the README in the zip file and in the OP. Here is a partial change log with the most important changes:
v.1.7.1 to v.1.8.1
Research cost for Energy Phasing, Doom Ray Tech, Photon Torpedos, Nightmare Torpedo, Quantum Drivers, and Singularity Drivers synced in all tech trees, where appropriate.
Changes made to Trade Focus 1 (In game name and its fixed stat block) applied to all tech trees where appropriate.
The stat block for Thalan Trade Optimization 1 was kept as is, as it looks like the change made in the base game is a bug.
Not a beefy update this time, but still a somewhat important one. There's been changes to many research costs for late game weapon techs. What Trade Focus 1 (renamed from Trade Stations to Trade Tariffs) does has also been modified.
The 1.7.1 version of this mod should be compatible with 1.8.1 (at least I see no reason why it shouldn't be), so if one is in the middle of a game go ahead and finish that one before installing the new version of this mod. But if one is going to start a fresh game under 1.8.1, I'd update the mod so it is in sync with the base game.