I've found that a quick re-grind usually brings new life to an old dim screen and it'll be as god as a new screen.

You'll be surprised just how easy it is to make a good glass screen that will match any commercial screen, Hopf included, in terms of brightness and usability.

Cost wise I think I'd rather make a couple of spare screens and just go for the normal glass unless you can get boro-silicate glass shheets at a reasonable cost. Optically it's additional brightness will be barely noticable/measurable and it can still get broken

Ian