If I upgrade from my Canon XSI to the T2i, will I get better image quality on long exposures?

Question

I bought an XSI about 2 years ago, and I am finding I can't do everything I want with it. Specifically I have started to notice the noise even at an ISO at 100, and I would really like to be able to do long exposure night shots to get the trailing star effect.

I have been looking at the T2i, but I don't know if it is a wise move. Is the overall image quality going to be better, and will I be able to do the long exposures for night shots? If not what camera would you suggest? I want to stick with Canon so I can re-use my lenses. I also want to be able to do time lapse photos. My XSI can only take a dozen (I think.) Is the T2i going to be able to do more?

I want to keep it under $1K, but if there is a much better advantage to going over a bit I am open to it.

Answer

CHeck out DXOMark. These guys analyze sensors and lenses in depth. XSi sensor here: http://bit.ly/pbbRmm T2i sensor here: http://bit.ly/n6ysLR

The T2i has slightly better low light performance than the XSi, but only slightly noticeable. It also has a slight larger dynamic range than the XSi, but it is also barely noticeable.

Canon doesn't offer a camera that will perform significantly better at under $1000.

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