While I do not do GB cosplay, I loved the movie and did order the Matty PKE as I also collect props (mostly classic Star Trek....phasers, communicators, etc.)....plus I play pretend with my 6 year old daughter who likes the first GB movie and often asks me to pretend I am Egon while she pretends to be some dragon or Pokemon or other creature, and I had been using a TV remote control to fill in for the PKE meter so I could "scan" her.
I am 48 years old. I started liking Trek when I was 6 or 7. I used to comb the aisles of the department stores back then in hopes of finding a toy phaser or communicator...no luck for many years, and when something did come out, it was grossly misproportioned and/or molded in color nowhere close to the actual prop (i.e. bright blue instead of black).
It wasn't until almost THIRTY YEARS later that they finally made toys that were 95% identical to the actual props AND they had authentic light and sounds.
My point...for a toy, the PKE is amazing. I understand the attention to the most minor details, as I am the same way about the Trek toy/props, and the frustration you die-hard GB enthusiasts must feel. And while the PKE toy is still pricey for a toy, it is amazingly accurate --I'd say 95% to my eye.
I guess whatever you collect, and whatever stock you place in judging it as a toy or more expensive prop recreation, the bottom line is are you happier with it or without it. If you obsess over the minor inaccuracies and will not be content with it as is, then I imagine you can either try to correct them or purchase a more accurate (and expensive) prop replica.
I realize this discussion begs the question, why didn't they just make it 100% accurate? I imagine this can only be answered by the engineers/designers and manufacturers of the piece.
Understand that I am NOT trying to belittle those that obsess over the small stuff....but having done so myself for many years over the Trek props, I can tell you that I spent waaaaaay too much time fretting over details on something that, at the end of the day, are simply toys...whether they are $500 prop replicas or $20 toys...they are all toys. And when the obsessing overcomes the joy of collecting or owning a piece of a movie/TV show you love, well, to me, it just sort of takes the fun out of the entire experience.
My humble two cents.