This is an absolute massive mistake if you do.
It just so happens that I have a co-worker that interrupts his prospects/customers. It really mind boggles me. He feels that it is necessary to be in total control of the conversation.
I cannot express how important it is for you to simply shut up and let them talk. Getting the most information you can is vital to moving the deal forward or getting a deal started. If I am a buyer and the salesman continuously interrupts me? I WILL take my business elsewhere. It is rude and offensive.
Do you really feel that it is important to not let the customer talk?