Tracks are hard to turn with only when poorly designed (If you wanna turn on a dime, might i suggest a halftrack with omniwheels at the back???
).
If you want to know more, I would suggest trying to contact FRC 1075, they have built a strong track drive for a few years (minus 09), and I am almost willing to put money on it that they will again this year.
Are they worth the time, money, and challenge though? This is a question only you are in a position to determine, based on your teams needs and equipment.