Matt,
In truth the rules call for a 1:40 figure ratio, which gives you an average battalion of 16-24 figures. However, the rules play
equally well for 1:20 scale, for those who like big battalions - a recent refight of Minden in 15mm and 1:20 proved that it worked admirably. In fact we stress that you can simply choose whichever figure ratio you and your opponent prefer, without it getting in the way of the game.
The main reason for pushing 1:40 is for us 28mm players - the cost of raising an army in 1:20 wouldotherwise be prohibitive! The smaller unit size also gives you the chance to refight larger battles than would normally be the case. I remember being daunted by Dave Brown's Napoleonic scenario books, where most scenarios called for armies of around 400 figures a side. This way we're giving guys who want to get into the period from scratch a fighting chance!
So, in short, you can use whichever figure scale you feel comfortable with. On my anorak website I've posted details of basing and unit organisation. Just double the numbers to reach the ideal size for a 1:20 ratio battalion!
Best Wishes,
Angus Konstam
www.edinburghwargames.com