Ever since I read the description on your PHALANX armor classifications, it has been bugging me. Here is my take on the issue:
* Combat Armour
Pretty obvious. Basic Tactical armor consisting of vest and helmet. Using advanced composite materials for stronger and lighter armor protection.
* Nano-composite Armour
This is advanced Tactical armor. This consists of Combat armor that has been enhanced with nanocomposite technology (which we currently have in production by the way and not based on any alien technology). Armor pieces include vest and helmet.
I am still trying to figure out where we get the boots from and what purpose they yield???
* Power Armour
This one has always been a bee in my bonnet. By your description, what you are wanting is a space suit.
I could spell out all sorts of problems with this, but I am not going to get into them. But, I will say this.
It is very impractical and definitely not combat effective (at least by the description that is given)
* Advanced Combat Armour
This category should go after Combat Armor and before Nano-composite armor. This would then make Nano-composite armor more inline with alien derived technology.
On another point of alien derived armor technology. If the aliens are technologically more advanced then us, and we then derive our own versions of their technology, wouldn't it go to say that the aliens would be able to counter their own technology? Even if it is slightly humanized? Our own armed forces know the pros and cons of their own equipment. So if it is ever duplicated, we know how to exploit the weaknesses. So, if the aliens see a 'version' of their own armor on the field of battle, wouldn't they know how to exploit its weaknesses?
I am not trying to put 'reality' into an already good game. I am just stating some obvious points that can go a long way of making the 2084 technology more advanced and feasible.