Over the years, clubfitting has taken on a science of itself. Long ago, we worried about the proper swing weight,length and grip size. Golf has evolved to a large variety of products, lie and loft angles to your launch angle and ball flight, etc. Most PGA Pros will give you good advice and know their limitations.
I used our Demo Days on the range with the Reps from the major companies like Callaway, Titleist and Mizuno to give their presentations of their product and fitting thoughts. It was also a big help for some tough problems that I might have to provide that perfect fit to hard to help member.
Last of all, when you are spending a lot of money on upgrading a driver or a set keep in mind; Are you purchasing compensation or correction ? If you are taking lessons, will the club improve the swing you have or the swing that you aspire to have? If you are in transition, you may want to explain that to your specialist before any final decision.