I'm testing out line doubling on a VGA monitor, the NES is just an emulator. So far everything works great except the monitor takes a split second to change resolutions, which doesn't mean anything for NES, most SNES, and most Genesis games, but with SotN every time I go into the menu I hear and see the monitor switch resolution (a standard TV would just do it seamlessly). I know the PS1 does 240p and 480i, but when it switches the menu resolution it's still in progressive mode, so I don't know why it needs to switch at all.
Also this monitor doesn't do interlaced modes, so when the Sony logo is displayed during PS1 bootup it looks like a progressive scan image with no jitter. I think I'll keep just emulators on the VGA monitor though, running at native refresh rates with MAME or Retroarch, so I better stop all this before I get tempted to start buying 480p upscalers.
But yeah, I've been researching the differences between PVMs and BVMs and since BVMs are so close to VGA monitors in their dot pitch I figured it was a good way to get some super fatass scanlines. They're a little too much for me, but the sharpness and clarity in the colors is ridiculous.