Two quick things I'd like to contribute to the discussion. When looking at the balance of a map, you have to in some way give weighting to the draws as often as not a draw is in fact a human victory in which they choose not to press for a win, rather holting the progression of the game to farm kills. The second thing I would like to point out is that the most popular maps in the current meta of the game do not necessarily extol the highest design principals for maps, rather they are a reflection of the inherent flaws within the state of the game.
Not exactly what you were talking about, but on the topic of draws. Just a random chip in here is that I think maps that rarely, if ever draw are really undervalued. If they are also balanced in terms of beast-human win ratio, then it's a really strong sign of a good map.
A lot of maps where humans can build a very strong shield, I would rate as somewhat flawed in their design. Usuallly it's due to the SH area being too large or too hard to access. By that I mean, in maps where the base pretty much defends itself and beast have to rely on either hours of sac-waves or the random chance of a lucky summoner or gate in order to win. It's much more preferrable if the players have to play a huge part of the defense such as on losthills or kinixxx. It doesn't mean they are not fun to play and good maps, however.
I think losthills and kinixxx are good examples. I mean, they draw sometimes, but there's usually always a real chance to defeat the opponent.