1) you can't play mineral only nats like you can LT. FAR TOO MANY players have played so much LT that, when faced with another map, they try to make their LT strategies work on those maps. So the first step is to try to change your playing style completely for different maps. It is my firm beleif that, if you know how to play a different kind of map correctly, it can be a very balanced game
2) i think a map like nostalgia has more of a time based advantage. For example, in an early game TvZ, the terran has the advantage (assuming he has good micro) with a strong medic marine contain. The zerg is limited to 1 gas for lurkers, which the terran can micro against. Although the terran will eventually have to run away, the delay allows the terran to get up his own expo and a few tanks etc. Once the zerg breaks his front and gets more geysers, then the zerg gets back to even ground. They key at this point is for the terran to use his early game advantage to keep the game even. Its far too easy for the terran to just let the zerg expo across the whole map to where its 4 geysers vs 1 geyser.
I recommend the sync vs siva game on nostalgia. Kinda shows how the balance changes from early game (sync uses M&M to cover middle of map) to middle and late game (siva trying to expand to many gas naturals and sync continuing to kill them off)
yea ~