I bought a back case from ebay and it came with 2 screen protectors from Terrapin. At first, I didn't even try them 'cause I thought they were lame.
But since I ruined my Vikuiti during its application, I gave Terrapin a try. I was positively surprised: it's thinner, better to the touch and more natural than Vikuiti. I tried scratching with a key several times and it resisted very well.
Just one thing: read the instructions, since the screen protectos is glued to 2 plastic pellicles, one on the back and other on the front. I didn't notice this and for a few hours I had a plastic pelicule on top of the screen protector and with this 2 layers the result was lame, eheh.
HTC Hero -> HTC HD2 -> HTC One X