Neck, I understand the data communications business because my wife is area manager of a corporation that distributes infrastructure materials in this field. She can be seen at BICSI which gives RCDD credentials as you are aware.
Being prepared and professional is absolutely important, but.......
all things being equal, they will buy from someone that they like.
All things NOT being equal, they will still buy from someone that they like! Companies (and people) buy on relationship!
It's not whether you do or do not use notes....it's how effective your message is. If people start leaving in droves, then your effectiveness needs to go under the microscope. Ineffectiveness COULD be because of unpreparedness, but it could also be the delivery or how people look at you. Are you friendly? Do people think that you REALLY care about them?
It's all about relationship!