1. How do you experience 'wider' scanlines? Is there less overscan area? Are there less black borders left/right?
2. What has the horizontal width to do with the number '200', since the number 200 indicates a vertical space.
3. '2 lines wide', I still don't think you can make the lines wider. (widescreen displays can though ) Can you describe this process?
I've looked at your game, starblitz, and on my laptop, with the brightness turned down, the scrolling looked nice. There are indeed a black frame every other frame so that causes flicker, but reduces the motion blur otherwise caused by a 'sample and hold effect'. The effect is nice, but I could imagine that it's unbearable on a crt with the brightness turned up.
My thoughts on 'Manual Flicker Optimization':
You should only use it if there is absolutely no other way.
If you use it, you should use muted colors (no max brightness), so the flicker is less visible.