Well I mostly never remembered seeing horizontal on-screen elements looking bent and convexly shaped when I sat level with the screen. So for me, I have recently been experimenting with a very minimal amount of curvature. So my newest presets (the ones with the graphics) use just 10% I think.
I can’t remember off hand the extent of curvature I used in my Soqueroeu-TV Special Edition presets but it’s very minimal. Those use the older Bezel Independent Curvature parameter.
Another reason I don’t like too much curvature emulation is because in side scrolling games it looks like you’re looking through a magnifying glass or fishbowl and it looks very unnatural to me when scrolling.
Curvature also affects some fine details of the image on the whole which you can see if you observe carefully some high contrast edges and switch it on or off.
Many presets I’ve seen have curvature set so high that it screams, “Hey look at me! I’m not flat, because I’m a CRT!”
Maybe my brain adjusted for it and since I got used to flat screens I’m just more sensitive to it but I’m sure it’s not something that stood out long ago so if making sure it doesn’t stand out means zero or very little curvature then so be it.
You should use what suits you best though. This is to a large extent subjective in terms of what one prefers over another. I think you might gain some quality and accuracy by sharpening things up just a bit more so that they are not blurry from both close and far viewing distances.
You can tweak the NTSC Resolution but you can also tweak the different sharpness settings. The NTSC Resolution can be used creatively to simulate all sort artifacts depending on the setting
If you’re using Mega Bezel Reflection Shader 1.8.0 - 1.9.0 the Horizontal Filtering sections seem to be broken at the moment at least for me. The controls don’t seem to work and the overall image is slightly softer than in 1.7.0 all else being equal.
That could possibly explain why your presets look softer. You might simply have to load them using 1.7.0 and they might look sharper.