Sounds good.
I think the hardest thing with WWI is to keep the game playable, while representing the problems of the higher level commanders to change the actions of units once committed to the fight.
If you can incorporate the problems of exploiting the initial break through, then that would be great. A big problem was the troops moving out of range (or observation) of their own guns, while getting hit by enemy guns and counter attacks. There are then the odd times that the attackers managed to hit the counter attack with their own guns, stopping and being able to hold the initial break through.
The troop density is also generally really high, with lots of troops on a small frontage - this is perhaps were miniatures work pretty well.
Please include stuff to work with smaller scale figures (I hope this is where you are going with half-company bases)