The perspex samples turned up last week, but I've only just got around to setting up a panel to try.


Display Testing by mc_mtb, on Flickr

The Frosted Slate Grey works pretty well, and only becomes illegible when I shine a 670lumen lamp directly at it, so it should be good once positioned suitably out of direct light with a hood.
Only issue with the perspex is you've got to buy it in a complete sheet, which means it works out pretty expensive, especialy since I'll probably only need under quarter of a sheet, so I'm waiting for somebody to drop of some frosted vinyl samples, which I'll try on some clear perspex to see how it compares before making any decisions.