It is definitely possible to have too much tint, especially when using a newer monitors because they almost always have a dark colored tube to begin with (versus the old tubes found in classic games, which were much lighter colored).
I have some plexi that is too far on the dark side. I used it on a Simpsons mini cabinet and I had to REALLY crank up the screen control to get the monitor bright enough to look decent through the tint. It is darker than all the tinted tempered glass that came original on some of my arcade games.
I have a pretty good sized stack of used tinted plexi, probably 8-10 sheets large enough for most arcade games, someone make me an offer (it will be fairly heavy/expensive to ship though).
Personally, I think tinted monitor glass/plexi is generally cheap and cheesey looking. Tint was mostly used on classics back when the tubes were not tinted. Modern games have tinted tubes and RARELY have tinted glass.
Wade