I'm also enjoying my 133" JKP 1.1. It's a clear upgrade from my previous 119" High Power (2.4) screen. Here's some quick comparisons between the JKP 1.1 and the High Power 2.4 surface.
1. This is by far the main reason for why I switched: My High Power screen had clear and distracting uniformity issues (I had my High Power screen replaced twice - issue persisted), there were both horizontal and vertical banding visible in bright scenes, especially if the camera was panning. The JKP surface has -almost- no visible banding (there are a few very faint vertical faint lines due impressions from the roller when the screen is kept rolled, they mostly disappear after the screen has been rolled down for extended periods).
2. My Sony HW50Es has slight white field uniformity issues, but they are less visible on the JKP 1.1.
3. The image also seems smoother, or even sharper as the surface is much smoother. There is less of a sheen/grainy effect of the surface.
1. I do miss the brightness of the High Power screen and I had to turn my lamp from low to high. 3D isn't as bright either.
2. Ambient light rejection is clearly worse. For me this isn't such of a big deal as I really don't enjoy watching movies/series with any ambient light as it just kills the contrast, even if the option would be "nice to have"
3. Even with the lowered gain I think the black bars in widescreen movies have slightly elevated blacks due to ceiling/wall/floor reflection (even if my room is mostly light controlled for the first 2.5 meters from the screen). This can be fixed by improving reflection control
In the end, I'm very happy with the switch.