Frag, may I suggest moving all the creatures of size 50k-60k all to 70k so there's no invaders spawning with dwarf-sized armors?
May I inquire as to the reasoning as to why you believe such a change would be beneficial?
From what I can determine, the overall effect of implementing this change is overall increased difficulty, through the removing of certain strategies and the increased toughness and power of enemies.
On one hand, the obvious problem with enemies the same size as dwarves is that after killing them, dwarves can use the armor they just dropped. On the other hand, the mod is already difficult due to the volume of sieges; a player caught off guard might welcome the influx of usable armor, and the presence of usable armor creates an interesting strategy for the player: to somehow kill the initial sieges of creatures with dwarf-size armor without combat, and then use their (probably sub-par) armor to fight off later sieges. This change would eliminate this strategy for better or for worse, and at the same time make the sieges harder due to the slightly larger enemies.
In addition, dwarves can only wear armor for creatures whose main size is size 60k; smaller dwarves should not be able to wear the armor of smaller creatures as far as I can tell from my modding experience and reading on the forum, meaning that there should be no need to change the size of smaller creatures based on the concern I raise above.
If people do agree that this change would be better for the mod, I will implement it.
Edit: Since the changes you described were trivial, I made a version of the mod with the changes you described in about 5 minutes.
http://dffd.wimbli.com/file.php?id=3601