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First of all, I want to make sure you are an UNDERpronator. When you say you underpronate, do you mean that you do not experience any pronation throughout the gait cycle? If so, then you need a shoe that will provide you with cushioning, since your body is not creating it via pronation.
Of the three shoes you mentioned, the Inspire and Kayano are stability shoes intended to provide support for runners who experience OVERpronation, that is, their body is generating plenty of cushioning via pronation, and what they need instead is to minimize some of that pronation.
That leaves the Pegasus. All of that said, I cannot guaranteee the Pegasus is the correct shoe for you. You will have to try it out and compare it to other cushion trainers to see if it is the best shoe for you.
FYI, the cushion equivalents for the Inspire and Kayano are the Rider and Nimbus respectively.