Hey Steve, is there any chance NPR carriers will make a return with the changes to NPR fleets etc? it would be really awesome to see them make use of carriers once more.  And honestly having NPR's surprising you with large fleets of missile fighters or beam fighters etc would be really fun.  Especially with a missile revamp making their missiles more interesting.

Probably at some point, but not for v2.2.

Guardians were added manually as a player-controlled race. I placed them on every world capable of supporting human populations and then generated random ruins on each world.

Depending on the extent of the ruins, I added greater or lesser numbers of defending units.

The only one I rerolled the ruins on were for were Mars and Titan.

The enemy might use AMMs that are no threat at all to ships though, with warheads with less than 1 damage to make them better at their job of destroying missiles.

Sorry this is a little off-topic but which UI mod is that? It looks kinda like solaris but not really...?

The current PD system only has overkill on a volley.  It doesn't have underkill as you just kept firing at the next missile until you ran out of PD guns. 
The new system appears to have overkill on individual missiles, so more PD is wasted.  It will also make underkill more likely as if all guns assigned to kill that missile miss, there is no further backup.  So there is more leakage. 
Missiles move so fast that using longer ranged weapons isn't going to get you more shots compared to gauss guns. 
So PD looks a lot weaker. 

I was skeptical, so I wrote a python script to simulate old vs new PD allocation schemes. This scenario has the best possible scenario for the old (current) PD allocation system: All missiles in one volley, and all PD fired as single shots, so no overkill. In both cases, it's 100 PD against 20 missile, with a 20% chance to hit for each shot.

After running each scenario 10000 times, and averaging the results, it seems you're correct. There'll be more leakers:

Old PD scheme:
number of shots fired on average:   92.1212
number of missiles stopped on average: 18.4002

New PD scheme:
number of shots fired on average:   67.1664
number of missiles stopped on average: 13.4576

(It assumes the PD allocated to a missile stops firing once that missile is destroyed, can't remember if that's correct. Was mainly worried about missile stop rate.)

PD also shoots so fast and so often that maintenance supply is going to be a problem.   I've moved away from using a lot of 5s recharge lasers due to the maintenance costs of rapid fire.  To compensate PD ships will now need a good fraction of their tonnage to be maintenance storage.  So PD is going to be more costly at the build phase and operation phase.

I agree however play testing will determine if this is the case.  This is just my interpretation of how what is written will play out.  I hope I am wrong. 

Well from my simulation, it seems like MSP use will drop, due to less shots being fired.

My code if anyone wants a look: https://drive.google.com/file/d/1P2RitplalMUODffKk2S4qUC_8bz_qqqs/view?usp=sharing