I think that having separate attrition rates for men and equipment would not be an immense job for programmers to add in but would add great value for modders. They can be left identical in the vanilla game version and hidden under the hood - perhaps just display an average attrition rate for a division like in HoI3, with a tooltip showing details if the player wants to see it. Thus it wouldn't add micromanagement to the player but its existence would allow modders an easy way to represent historical differences between countries when it came to supply, repair and maintenance of both soldiers and equipment.
Ideally, each piece of equipment would have its own attrition rate, influenced by reliability tech, weather, and terrain. Then you'd have a basic attrition rate for soldiers. Modders could then implement high attrition rates for famously unreliable pieces of equipment (Panther anyone?), not to mention implement national difference. Germany was pretty famous for lack of spare parts - according to post-war study, up to 70% of "knocked out" tanks were sitting at repair depots purely due to lack of spare parts, not because they had been destroyed.
TL
R have separate attrition rates for soldiers and hardware, hide it under the hood so it won't bother average player, while giving modders more tools.
Ideally, each piece of equipment would have its own attrition rate, influenced by reliability tech, weather, and terrain. Then you'd have a basic attrition rate for soldiers. Modders could then implement high attrition rates for famously unreliable pieces of equipment (Panther anyone?), not to mention implement national difference. Germany was pretty famous for lack of spare parts - according to post-war study, up to 70% of "knocked out" tanks were sitting at repair depots purely due to lack of spare parts, not because they had been destroyed.
TL