Oslet, I would actually suggest trying a higher ISO (e.g. 1600) if you aim to use short exposures.
The ISO value is basically a tradeoff between read noise and dynamic range. With higher ISO comes lower read noise, which is always nice, but this comes at the cost of lower dynamic range. Actually, ISO is just a way of describing the concept of gain, which is the number of electrons (think photons) that must be accumulated in a pixel in order for its digital value to increase by one. High ISO gives low gain, meaning that the pixel value will increase more per electron and hence you get a "high sensitivity". In this case, fewer electrons are required for reaching the maximum pixel value (this value is typically around 2^14 or 2^16, depending on the camera), and hence the pixels are more quickly saturated. Faster saturation gives a smaller difference between the minimum and maximum number of photons that can be registered, corresponding to a lower dynamic range.
A sufficiently high dynamic range is required to avoid saturation of important parts of your target (like the core of a galaxy) during a single exposure. So if saturation is a problem, you should lower your ISO. But when you do short exposures, you are not likely to reach saturation even with a relatively high ISO. So then it might be better to use higher ISO so that you can benefit from lower read noise.
Anyway, this is my (non-expert) take on it. The best thing is probably to experiment to see what works best for your equipment and conditions in practice.