Originally Posted by noob00224
Haven't seen the ST HC grey in person, but I don't think it's similar to the 3D. It's darker and has less ALR properties:
It's very hard to take pictures that provide an accurate representation of screen materials. In particular, ALR material must be totally flat, preferably stretched (which may be hard to do for small pieces of screen materials). Also, the direction of the light as well as the camera angle will make a big difference.
Here are two pictures that I took, comparing a letter-size sample of Silver Ticket HC Grey, with a full size piece (135" Designer Cut) of Elite Cinegrey 3D. Below them is a sheet of white paper as reference.
The first picture is with light coming from the same angle as the camera, so is representative of light coming from the projector.
The second picture is with light coming from the side at a fairly steep angle, and is representative of ambient light. The camera exposure is adjusted to provide the same brightness of the whit paper between the two shots. A darker material in the second picture would indicate a higher ambient light rejection, and both materials do a decent job.
I would challenge you to identify any meaningful differences between the two, either in terms of brightness (first picture) or ALR capability (second pictures).
EDIT: A some angle between the two extremes, the ST HCG does look a little darker than the 3D. You can consider that to be an advantage or disadvantage, depending you your viewing angle requirements and ambient light directions.