You kinda could. They way I invivision it is a low kit unit would have the same actor for all 3 ranks…. Then if you get a tech for spearman increased body armor say, all spearman would “promote” they would have to go back to rank 1, but then the “new” unit would have a new actor…. So you may need 9 templates just for that civ’s units if you have 3 “kit” upgrades.

Sadly, we can't currently only change props from techs, we can only swap in a whole unit actor. So, the best you could do is "levels" of gear, like "Basic Kit" -> "Medium Armor" -> "Heavy Panoply", which is fine and can definitely work. Then attack could increase by ranking. 

Best would be to add a poll to the thread @Baelish

For the context, please read https://gitea.wildfiregames.com/0ad/0ad/issues/8599. I want to explain why I choose 5 gatherers for small ruins. Many entities inherit from template_gaia_ruins.xml, with different amount of stone and metal. I will do a summary of them: STONE stone_statues_kushite_bird, stone_statues_kushite_lion, stone_statues_kushite_ram 200 standing_stone, stone_statues_egyptian, stone_statues_kushite, stone_statues_roman, stone_structure_small 300 stone_column_roman 400 column_doric, roman_rostrum, stone_statues_persian_lamassu, stone_structure_farmstead, stone_structure_house, stone_structure_tower 500 METAL metal_statue_discobolus, metal_statue_poseidon 400 metal_statue_apollo, metal_statue_isis, metal_statue_wolf 800   As reference a small cut of rock has 1000 of stone and 12 gatherers, so I thought that would be a good deal to set 5 gatherers for something that has around 400

may even take it a step further, custCWA chart - Sheet10.pdfomize the weapons too (not the graphics though, just the stats, length, speed etc) based on this chart, if you find it fairly accurate.