The Do-More advantage is cost, ease of use, and support for me.
Cost: Do-More doesn't have the extravagant annual costs of most of it's competitors.
Ease of use: The Do-More designer is far superior and easier for me to write code with than RSLogix
Support: Where else can you communicate directly with the designers?
Working with Do-More after working with an AB product is like tasting freedom after leaving a socialist state. You can't help but to love it.