Be warned that Sidekick's algorithm is very Twitter-centric and so if you have a huge presence on non-Twitter media it may be biased against you (or biased for you if you're JUST on Twitter and not much of anything else, conversely).
KickTraq is a little less volatile but as far as I can tell it's just projecting out from the curve of your last couple days, so it really doesn't take the bathtub model that many KS's follow (intense beginning and ending days and listless middle weeks) into account completely. OTOH, I would certainly recommend making sure that at least some of your updates are going up on KickTraq. It's a very well-trafficked site with a lot of features.
There's also KickSpy, which is so far the only predictor I've seen that does attempt to emulate the bathtub by comparing your campaign against past campaigns determined to be similar.
All the predictors are wildly inaccurate at the beginning of the campaign and get more accurate as they go on, and if you are of a nervous temperament I definitely recommend resisting the urge to check too often and taking their numbers with a sack of salt.
That said, they can certainly be helpful not only to your campaign in progress but especially to your pre-campaign research to determine your initial ask, where to set your expectations, etc.