Mark,
if you go back through the pages of previous posts you will see this topic has come up before.
I am working on such a ruleset. I've playtested my ideas on a Lexington battle and they seemed to work fine. I am still quite far though from having a form of the rules that might be playtested by others, let alone marketted. In the latter context I have had a brief conversation with Caliver Books about whether they'd be interested in the AWI version and they would.
regards
EC