As much as I appreciate the little adds on and comments from the History channels buffs, that doesn't answer the questions relevant to the rules system or more specifically the adjustment to the basic rules as found in Blackpowder and modified in The Last Argument of Kings.
In LAoKs, Cavalry verus Infantry rules have been modified to allow a die roll of six which causes auto-disorder (basic rules) to throw back cavalry (LAoKs rule) a distance equal to the amount of movement left to the unit. Basic rules never change the number of dice a unit throws no matter what their status is, disordered, shaken, whatever- they always throw all dice available when shooting. In LAoKs several units now throw more than 3 dice, due to most receiving First Fire and several having the rule Platoon Fire. Combined with the 45 degree firing arc, and the list rules that require several armies in LAoKs to take a certain percentage of Cavalry these units have little effect and are auto-shooting targets to force BDEs off of the table. (Infantry)Throwing 4xd6 when disordered or shaken and only needing one to be a 6 to throw back Cavalry results in several mandatory Squadrons to be limited in use, a lot of painting for not much play.
Don't need the tactical advice on cavalry usage, I think I have that part covered, interested in some comments from people who've read the rules and their ideas.
You didn't like my suggestion of the house rule of extending the modifier for a disordered unit so that a 6 wouldn't cause disorder, then?
Well Big Mike's alternative might suit. It doesn't really need someone who has played the period to recognise a solution to the problem. Bouncing ideas off each other usually brings out a suitable combination for the questioner.
Sorry. My mistake. In the LAOK supplement it was always my intention that only formed troops ( eg: not shaken or disordered ) could use Platoon firing. It relies on good organisation and training to achieve Platoon firing effectivley and so units who are in disorder or falling back due to casualties etc would not be in a position to fire effectively ( hence the -1 in the original rules as well ). One for the errata.
Platoon firing was introduced in order to achieve the "Quebec" effect, where one or two volleys would decide the fire fight. Platoon firing combined with first fire gives five dice, which is enough to shatter an average unit and so you could achieve what Wolfe did, or simulate the British first fire at Fontenoy, for example.
With Cavalry, the normal Black Powder rules really reflected how cavalry were used in the late eighteenth and early nineteenth century ( charging full tilt into whatever was in their way ) and we needed something to show the transition from Carocole through "charging" at the trot and discharging pistols to full blown charges with the sabre. At battles such as Minden, French cavalry have adopted a charging role ( not firing pistols and coming on at the trot as they did at Dettingen ) but are still not effective against infantry, although Prussian and Austrian heavy cavalry are begining to become a real threat. Under BP as it stands, charging cavalry recieve 3 dice of fire when charging infantry and will almost always close ( although they may do so disordered etc ) Subsequently, they have the upper hand in melee. When playtesting the Great Northern War, for example, Swedish cavalry became unstoppable! The additional rules for cavalry versus infantry ( 6 forces them to withdraw and secure flanks ) were designed to make infantry feel confident enough to face cavalry in line. If you feel any of the additional rules are not working, try games without them and see how you get on. You do have to achive a balance between realism and having a fun, balanced game.
Historically, a huge proportion of the armies of the early eighteenth century were cavalry. This gradually reduces as the century wears on, and hence to high percentages for cavalry in the army lists. Cavalry were most often used to drive off the enemies cavalry, exposing the flanks of the infantry. I appreciate this is tricky on even the largest of wargames tables, but that is early / mid eighteenth century warfare for you. My suggestion is try your games without the "6" causes a withdraw rule and see how you get on. In our playtests I felt cavalry were too "Napoleonic" and wanted to reduce their effectivness. Everyones perception of history is different so do what works for you and let me know your thoughts.