This is the SR300's fancier brother. Based on the same frame and roasting the same amount of coffee as the SR300 the SR500 roaster adds in more control for those looking to experiment and learn. It offers you the choice of setting low, medium or high heat, and a rheostat for adjusting fan speed (+/- 10%), as well as a digital timer. This compares nicely with the I-roast 2 machine but has a quieter fan. The I-Roast by comparison allows the user to save roasting profiles, a feature that is used by some home roasters. Buy the SR300 if you are getting this as a gift for a general coffee drinker. Get the SR500 if you are a coffee geek (like us) who would want to see how heat control and fan speed can affect the roast. If comparing to the I-Roast choose this model if fan noise is an issue and choose the I-Roast if saving roast profiles sounds like something you might be interested in.