SD Overall Suggestions

Well, not signing yet, but that's because it's ALL ME.

Application Based Technology

Instead of buying up tech categories (and then getting into questions about "how can we not have invented algebra despite building cutting-edge death rays?") buy up application categories.

Application categories would be things like "I can build tanks/giant robots/mecha/etc, allowing certain customizations ("added caps"), or passive boosts to various categories, purchasable by SP. This would cover tech primarily, but could in theory be extended to magic, given that in theory magic should be reproducible and there really isn't that much of a difference, on a large scale, between a grenade launcher and an enchanted bow firing fireballs or something.

Combat Effectiveness

The current system has a very small margin of error between a unit being 100% functional and taking enough casualties to be combat ineffective. Instead of using this system, you could combine "hit points" and stamina/will to fight into an overall Combat Effectiveness track, which increases or decreases depending on base unit type, their esprit de corps, and other modifiers, representing a combination of logistical support, casualties, and so forth.

Attacking, certain combat maneuvers, and taking hits would obviously decrease combat effectiveness. A unit at 0 has too few people capable of fighting to meaningfully defend themselves, making them incapable of putting up a meaningful fight and vulnerable to actually taking losses. In this way, battles will generally cause less inherent risk (unless avenues of retreat are blocked off, or an organized retreat is turned into a rout) allowing force preservation to be significantly easier.

Just a thought.