In my experience, most white screens have very little difference to them at normal viewing distances as long as they have similar characteristics.

So, a typical low gain screen will have a gain between 1.0 and 1.3 or so. While this can add a fair bit of brightness from the lowest end, to the highest end, the reality is that these specifications may not be dead on accurate as they are not subject to legally binding measurements. So, your 1.3 gain screen (especially) is often only a 1.2 or 1.15 or even a 1.0 gain in independent testing.

The exception to this is typically Stewart Filmscreen materials who maintain an extremely high standard for their measurements and tend to be very close to accurate. But, you pay the price for their quality.

At the lower end, the materials tend to be very close to price/quality appropriate and in parity. As well, while it may seem like a 10% or 20% gain in brightness should be quite visible, it rarely is.

There is nothing wrong with the material on your current screen, and it likely is comparable to the materials on a Silver Ticket screen or a Elite Sable Frame screen in white.

I've used and seen a ton of various screens over the years, and the only screens that truly jump out at me are the ones which are positive gain or ambient light rejecting. Mostly because both of these are using particles in the screen which introduce speckling and sparkling to the image which is clearly visible and detracting from image quality.

White, low gain screens, typically do not have this problem and many low gain white screens are actually closer to 1.0 gain then their advertising may indicate. On top of which, your eyes aren't great at noticing a 10% difference in brightness.

If you got some samples from Stewart, especially higher gain and lower gain samples, you would likely see more of a difference. But, I wouldn't expect much around the 1.1 gain threshold to provide much visible difference.

I see you posted over at AVS as well. I would dig through their screens forum as they do have some threads that compare actual measured brightness of various materials.