A lot depends on why you are disappointed.
A lack of info from your current consultant? you don't like her cards? she's late with orders and delivery?
Or does it seem that the other consultant offers more free stuff, better deals?
Either way, if you have been with the current consultant or demo for over a year, why not talk to her? Tell her why you are disappointed. Give her a chance to make it right, if possible. (what would you want if you were in her shoes?)
There are also some people who work with multiple demonstrators. Some of them are my part-time customers. I do my best, and hope that one day they'll decide I'm so awesome that they become my full-time customers!
Would this work for you? At least while you check out the grass on the other side of the fence?