Stacking in the more recent games I have done is 600 cavalry but let me ask you something: if 400 cavalry at Marengo could run over an entire brigade of Austrian grenadiers just imagine what 1000 could do?

I think that people forget how powerful cavalry were if infantry was not in square.
Cavalry may not be a one shot deal but they also are vulnerable to fire. Trying to defend out in the open is an invitation to being hit by cavalry if not in square.
Now as to what is the correct stacking. Al Amos and I discussed this long ago. The discussion resurfaces quite a bit.
I went with 600 cavalry and 1600 infantry. The confines of a hex are not a boundary but merely a point of reference. The unit is in that area. That is why there is a ZOC for most units.
Players that pack in their units trying to achieve a "killer stack" find themselves hit multiple times by artillery.
I have tried playing the other format of play (H&R) and find that the units get in each other's way. In one game I played I had 2x the usual number of units and defense in depth meant "sardine can." Trying to get a unit to the front line while pulling another back became an arduous endeavor. Routed units didn't rout through a unit - they remained stuck at the front.
David Andrews did an admirable job in our Leipzig game of setting up a defense line using squares and guns. While I agree that this was not standard practice I think that whenever you get into total historical accuracy with any game you will find it comes up short.
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Generalfeldmarschall Wilhelm Prinz Peters von Dennewitz
3. Husaren-Regiment, Reserve-Kavallerie, Preußischen Armee-Korps
Honarary CO of Garde-Ulanen Regiment, Garde-Grenadier Kavallerie
NWC Founding Member
For Club Games: I prefer the Single Phase mode of play. I prefer to play with the following options
OFF:
MDF, VP4LC, NRO, MTD, CMR, PR, MIM, NDM, OMR (ver 4.07)