Here in the UK we use a lot of Trivex/PNX and find it to be an excellent material for rimless mounts.
The only drawback I've found is the length of time drilling takes on a CNC machine compared to poly or plastic. I use a Berkshire optical Optidrill CNC, (I think it is distributed by Salem optical in the USA).The problem is the drill is set up to take tiny 'pecks' at the lens to stop the material melting onto the drill bit, which causes problems with hole sizes, or collecting at the top of the drill shank forming a type of collar, inturn wrecking the lens by drilling a huge countersink which you didn't want. Yes, I've learnt from experience!!!
The overall finish and durability seems just as good as poly but with the benefit of a better ABBE value.
Also it doesn't seem to be any great deal thicker than poly even though it is a lower refractive index
The price at last is also coming into line with poly as well