I really like these shoes.  By a size up.  I was concerned about support but these are very comfortable.  The insole is solidly built in so don't think you are going to replace it and putting one on top won't work. It would be too tall for the shoe. However, the insole that comes with it seems fine and the shoe comfortable . I really, really with there were half sizes. That would be much better. I bought several colors after trying my first pair!