Many years ago a friend of me, Niklas Zetterling, developed a general division scale ww2 battle system inspired by Dupuys 'Numbers and predictions in war'. Up to this day this battle system is the most realistic that I have encountered (though I regrettably don't play that much serious consim games).
In short each unit has a number of steps (usually six for a standard inf div) two attack and two defense strengths, maneuver and prepared, an operation point value, an AT-rating and a type. The turn was I go/You go with combat as part of movement (both movement and combat cost op, and displaced enemy units leaves an op marker behind that will have zoc up to that point.
Turns were 1/2 weeks and hexes 16 km.
It was a very clean system with quite few special effects and such, while combat resolution was rather complex - we usually used computer support!.
Anyway, the bottom line was that it worked surprisingly well on any tested situation, without a lot of tweaking. I was especially impressed over how it worked on the eastern front, where the scale of operations, rate of advance and even type of mistakes made, corresponded well with the historical data. It also scaled nice as long as we didn't venture to far into the tactical realm.
It was however slightly cumbersome to play Barbarossa on division/brig level with half week turns and 16km hexes....
What was used from Dupuy was mainly the method of getting a base strength of a unit by adding a calculated kill-value (well, two - mobile and static) for each single weapon in the unit, and adjusting with his national efficiency factors, adjusted for different branches (like SS and Luftwaffe field div....)