The Canvass system is terrible. It's almost impossible to tell whether or not an idea has already been submitted by someone else, is time consuming, doesn't allow us to easily add screenshots etc.
A good support / development / technical team will be familiar with the features and bug requests reported & documented and be able to take customer feedback and apply it in the right way. By all means offer a facility like Canvass for those who want it, but then manage it.
Allow customers to send you feedback by email, and then apply that to the correct place. You can even send a link back to the feature that you've assigned so they can track it.