Here are my general notes on the current tech tree. This is for the 5/23 1.55 version.

General

Its really frustrating to hover over a tech and not be able to actually highlight what the things inside the tech do. I want to be able to hover over the "starbase factory" and see what it gives me.

Engineering

Starbase Line

• Starbase Defense System feels a little stacked. You could probably take one of those modules (maybe fortification module) and move that Starbase Com Stack.

Asteroid Mining Line

• Resource Extraction Doctrine I think can be removed, and its elements moved to Xeno Resource mining. This tree is pretty questionable as to its benefits, this helps tighten it up a bit.

Artificial Gravity Line

• Orbital Manufacturing still does nothing, it should be removed or given something.
• In general this seems a pretty solid line, overall I like it.

Subspace Scanning Line

• Subspace Scanning: why is the promethium drive here? Seems odd its not in the Artificial Gravity line.
• Subspace Streaming: Slipstream Accelerator is noted here twice
• Anomaly Detection: The "Thulium" sensor array....doesn't seem to require thulium.
• Overall this line feels a little scattered, its a mishmash of some abilities in there, especially since most of the "sensor" abilities are in the Starbase Line.

Colonization

Planetology -> Space Elevators Line

Planetology -> Xeno Biology Line

• Environmental Engineering - I understand the flavor of putting the various "farms" here, but honestly these speciality farms are so niche I'm not to go get tech for them. I would rather these were all under the Xeno Resource mining type techs....let that line handle all of these specialty buildings.
• Biomass Resequencers can likely be drop, either drop the food bonus entirely or give it to Adapted Crop Engineering. This line feels a bit too long.

Xeno Research Line

• Weak AI and Orbital Research Labs are both pretty weak (especially when your talking about spending science to get science). These can be merged into one.
• Artificial Brains and Post Sentience are also weak individually, and can be combined.
• Technological Singularity: Its an awefully steep price tag in science to get a meer +10% more science.

Precursor Archeology Line

• Xeno Computational Theory - Weak, can be removed.
• Stong AI - Its in a weird place in the tree, this seems a natural progression of the Xeno Research Line
• Precursor Artifact Mastery....it gives Precursor Nanites which unless I'm missing something aren't all that special, not if this tech is really needed.
• In general I like this line, relics are strong enough taht committing tech to them specifically is a worthwhile endeavor.

Warfare

Directed Energy Weapons Line

• Photonic Alignment: Doesn't get the +1 Laser Attack like the equivalent kinetic/missile techs. Now that seems to be intentional as each line has gaps, but I would argue as this is the earliest its the biggest "weakness". By the time the other lines miss out of that +1 attack general that benefit matters a lot less.
• Phasor Beams: The Phased Cannon is 100% worthless due to the Experimental Disruptor Bank under Disruptor Beams several techs back.

Railgun Line

Avenger Missile Line

• Missile Warfare Mastery - Does nothing

Armor Defense Theory Line

• Organic Armor - The "Kanvium Laminate" ship part has exactly the same name as the starbase module 1 tech back.

Energy Deflection Theory Line

• Shield Regeneration - The name implies that my shields will start regenerating in combat, needs a new name.
• Shield Augmentation - The force field projection starbase module adds 10 shields....that's 10 HP for 3 elerium and a module, far too weak.

Space Doctrine Line

• Space Doctrine actually is pretty stacked up, you can likely the +1 max policies back 1 tech.
• Battle Cruiser Doctrine - Everytime I read this I think Battleship. Just make it cruiser doctrine.
• Flexible Bulkheads and Extreme Miniturization is a very large jump in components, seems odd to have these back to back.
• Orbital Repair: comes a bit late in the game, as hp repair is pretty weak compared to shields or other ways to mitigate damage.
• General: I've always questioned if each ship class should just lumped into own line like this, rather than spread over other prereqs.

Governance

Leadership Recruiting Line

• General: First impressions, this is a very stacked line when you combine the minister AND all the policy slots. I'll play this out, but my gut says this is a bit much.

Xeno Entertainment

• Definitely the biggest "hodge podge" of abilities imo, feels a bit scattered.

Diplomacy Line

• Diplomacy: You can likely steal the +1 max policy from leadership recruiting and put it here, I think this line needs encouragement to go down, whereas the leadership line has plenty of juice.
• Trade Pacts: Fairly weak tech with only a policy that isn't that great.
• Alliance and Eminence can be merged. Hell you can properly merge this AND trade pacts.