One of the key advantages with this approach is that modders can give units weak-points so that even the toughest unit can be overcame if you employ the right tactics. This is all in addition to the old favourite of making a warhead more effective against certain armour types than others. Below is a concept sketch of a modern day tank. It is very easy to make the tank weaker at the back than at the front simply by making them separate sections.

This will be great for the 'realist' modders but also has more general appeal.

The engine automatically identifies which section was 'hit' but damage may still be caused to nearby sections.
How effective a warhead is of course down to the warhead INI. It's effectiveness will be defined against a list of 'materials' which mean 'armour types'. The actual types haven't been decided yet (and are a hot topic) but here's a plausible list:

Flesh -unarmoured living
Alloy -unarmoured non-living
Immune -special case. Ideal for weapons
Steel -normal metal armour
Tracks -used for sections specifically prone to mines
Cobham -Improved metal armour.
DP -Depleted Uranium. Just another type of metal armour
Concrete -for buildings etc
Soft -for unarmoured buildings
Special -spare