Is it worth sipping a drink during workouts other than water?

Unless you are working out at a high intensity for more than an hour there is really no reason to drink anything other than water during your workout. Water is your best bet. After you work out, just make sure you have a nice healthy snack. Don't wait a few hours until you are starving!

Absolutely, some guys who are trying to gain muscle drink carb drinks during training and this is fine (although they could probably add a little bit of whey protein or something to it). But if you are trying to get or stay lean, why take on the extra calories if they won't benefit your performance?

The obvious advantage of a carb drink comes not necessarily with a high intensity workout but with a higher intensity, long endurance workout (an hour or more). The other instance in which you might want a sports drink (a carb & electrolyte enhanced tasty drink) is when there is humidity and/ or there is temperature that is greatly increased. The body is provided a little extra carb (energy) as well as a replacement of the electrolytes that leave the body from sweating if it is a sports drink.