You'll find probably as many mix recommendations as there are hedgehog owners. One of the biggest reasons we recommend a mix is because hedgehogs do not take to change very easily. Some will go on hunger strikes if their diet is changed. Should a food suddenly become unavailable and you run out, hopefully 1 of the 3 of a mix will still be around.
For me I use Innova SR, Innova Lt, Pet Promise & Newman's own currently. I've used a variety of others in the past as one of the foods but typically the first 3 never change.