In regards to the Combat Armor, looking at the stats, I can't tell any reason to use Personal Armor given you can buy this and get virtually the same protection. Really like the idea but think I'd like to tweak it to make it useful but also give a reason to manufacture Personal Armor.
I got some ideas to fix this.
First I suggest making the Plasma damage modifier of the Personal Armor much lower than for Combat Armor, leading to the Personal Armor to be much more resistant to Plasma Weapons than this Kevlar thing. Given the fact that aliens use plasma weapons almost exclusively, I would think this would be pretty strong reason to swap your Combat Armor with Personal Armor once you have it. The explanation would be that since aliens want to be able to perform combat inside the UFO without destroying it, they would tailor their alloys to make them plasma resistant.
Additionally the Personal Armor could also have reduced damage from fire. Given the fact that it is made from non-flammable metal alloy which has some pretty impressive heat resistant abilities (the alien Battleship can zip over 1500 km at 5000 km/h in the full Earth atmosphere without turning into so much molten metal and still be functional enough to break the X-COM base's hangar and access lift doors and deliver all the troops in it into the base, see
https://www.ufopaedia.org/index.php?title=Battleship; especially the Alien Retaliation section on that page; the explanation would be simple, Alien Alloys make for an excellent heat shield), I would expect that an armor made from it would handle fire much better than a Kevlar suit. That would also explain the extreme resistance to the hot plasma spitted by the alien weapons.
Next, the Combat Armor would be really heavy, requiring a strong soldier to wear it or suffer the resulting encumbrance. The alien alloy properties would allow for the Personal Armor to be much more lightweight, allowing any soldier to wear it without any encumbrance effect (it would be as light as Coveralls).
And last, the Personal Armor could see some strength upgrade and maybe more even distribution. Maybe all its stats having 60 armor strength (or maybe making the under armor only 50 or even 40 armor strength but the rest being 60). This would make it enticing from the protection point as well while not removing the enticement from the Power Suit (which has the front armor set to 100). The power suit could also be upgraded to 100, 90, 90, 80, 70) to give the player a reason for its increased cost.
