I have both. One bathroom has 1/2" starphire the other is 3/8" I like the heft of the 1/2" even though it is not necessary (like HP in a car, after a certain minimum it really does not matter except to the owner). Hinges are designed to hold 1/2" and your designer should be able to pick the right ones. weight and width are not a problem. 3/8" is perfectly adequate so we used it in another bathroom. I guess this discussion is similar to the 2cm vs 3cm granite. 2cm works perfectly well. so does 3cm. If you like the heft, get the thicker material.

Thank you all so much for sharing your experience, which is very helpful. I'll go for the 3/8" glass. For complete frameless, it seems better to use the 3/8" one. Since it's heavy, is it better not to have a glass door too wide? How wide are your frameless shower doors? Do you have vertical gasket installed at the fixed panel or door? If not, is it a concern that water might splash out through the vertical gap? Thank you very much.

What’s the criteria for deciding to use 1/2” glass vs. 3/8”? Length of unsupported glass, height, . . both? Or the length of the door return assuming the door is mounted on the wall. Something else?

@kharten The reason I bring it up is because we are building a new house. I chose Showerguard glass coating, and then I learned about low iron glass. I researched the difference between regular and low iron and realized how much better I liked the low iron. Regular glass has a green tint. Since our shower has a window and white tile, I didn’t want the green tint. Even though it’s pricier, to me it is worth it.