Almost all of my current armies are 15mm - and that's essentially because the aesthete in me loves the look and feel of individual metal miniatures, thinks that 20mm can get a tad "cramped" on a table this size ( probably the wargaming equivalent t the issue in train modelling of " tail chaser" layouts!) - and finally, my eyesight isn't good enough to enjoy the really small scales without a great deal of additional magnifying equipment!
So, 15mm on a 6 X 4 table it is. But the other problem for wargamers is.. well let's give it its proper term.. Megalomania
We want to command vast forces, at very high levels of command - with only a few compromises. This is why I love Fire and Fury rules for the American civil War http://www.fireandfury.com/products/desc_ffrulebook.shtml
(ACW in wargamers anorak short form). It's also why Rapid Fire
http://www.rapid-fire.uk.com
rules for World War Two ( WW2 ) are so satisfying. But I'm still going to struggle to re fight waterloo on my table..or am I. More of that in a later post!
If anyone has any thoughts or experiences about getting the most bang for one's buck out of 6 X 4 with 15mm - I'd welcome your comments with arms as open as a French defensive line in 1940!