have to say I've never owned or used a counter - always imagined they were large box-like things with strap that went round the neck. I think you should use it in the shops - so many people I meet in charity shops are keen to know why I use a torch, why I look at the bottoms of glass, it makes for an interesting life. How dull to be ordinary, to let life pass without taking an interest and having an inquisitive mind - that often you can share with others.
The issue with drinking glasses is that perhaps more than most other designs, copies abound since most of the historic shapes are appealing and are reproduced ad infinitum - when most of my glass went, it was my drinking glasses that I kept.