The button cam and the eye glass cam have different strengths and weaknesses, which pretty much determine where each may be best used.
In new home and apartment shops, as well as most car dealer shops, for instance, the objective is to be able to keep the target SA in the frame, but to be able to turn your head to look at some object that the target is pointing out. So, the button cam, mounted to a shirt, is typically required so that the target remains in the frame at least 75-90 percent of the possible time. (Time spent sitting in a car, for instance, does not count for "framing" purposes.) Some types of shops both do not require the shopper to look away from the SA to appear to act normally, and/or require framing a target who may be behind a rather high counter, or in a booth or be standing outside of the shopper's car window. In there cases, the glasses mounted cameras give real advantages. These include, bank or retail "drive thru" transactions, hotel check-in/check-out, automobile rental counters,medical/dental offices, and some other retail applications where the objective may be to scan the products on a display including very high and/or very low shelves, for instance.
As far as I can tell (and this includes discussions with dozens of video shoppers and most of the active video managers/schedulers) the button camera, shirt mounted, definately will get more shops assigned. As the industry broadens its scope (new client types emerge) I can imagine more parity in assignments where the glasses cam will be preferred. But we are a long, long way from that day. In the mean time, many video MSCs will loan a glasses camera for the relatively few shops that really require it.
For shoppers who really need to wear their prescription glasses, substituting clear lenses with the cam attachment is not going to work, though. You can have a set of glasses fames with the camera fitted with your prescription lenses, but, in my case, that would bring the total cost of the glasses cam option to above the current price of the button cam.
Based in MD, near DC
Shopping from the Carolinas to New York
Have video cam; will travel
Poor customer service? Don't get mad; get video.