Bare 5mm Elastek Super-Stretch Diving Hood

Jennifer:

Is this hood what you would recommend to wear with the 7mm full Elaste wetsuit? I rented a generic hood and the bib bunched up so I got cold water down my back because the neck didnt seal properly. So I dove in the 7mm with no hood and am thinking that the 5mm will be warm enough. If the water temp. is really cold I have a vest with attached hood in 7mm. What is your return policy if I try the hood on and its not the right size? I could wear either a S or a M according to your sizing chart. Thanks for any suggestions before I order. Jennifer