OK, this image shows MadMab/XPort's SNES9x port playing on Sony PVM2950 - output 640x480 VGA (Frosty Cable), through an Extron Emotia, which switches the output to real 240p.

After looking at these side by side, you can see two things. In terms of image softness, the 'real' output it somewhere between the bilinear filter and the natural softness of 480p. Though, this is so close it doesn't really matter.
The other issue is that SNES9x on the Xbox outputs a 512 pixel width and doesn't have an 'aspect ratio fix' like BNES does. I've tried manually stretching the image size to 640, but this introduce image distortions when playing games.
This aspect ratio fix is one feature that would be great to add to SNES9x if its possible. 
There is a way around this though, but only if you are using an HDTV....
Below are more pictures, this time of SNES9x on the Xbox outputing to my LED.
Note: The Xbox outputs YUV component, which is then transcoded to VGA by DVDO iScan HD. The signal is passed through an SLG3000 for scanline emulation as well. This model DVDO is know to soften the image, so I may eventually try this out using the Xbox 'native' VGA output - via a Frosty cable.
Xbox - 480p
The softness here is likely due to the DVDO iScan HD. For more info on that and other deinterlacing devices, check out this site:
http://retrogaming.hazard-city.de/Xbox - 480p - with Scanlines (SLG3000)

With scanlines. (See everything looks sharper)

Now, the next two images shown are with me 'tricking' the TV into displaying the SNES emulator output 640 width instead of 512. What you do is set your pixel perfect size in SNES9x - 512x448 usually, then activate 10x11 pixel size. <- this is important. Then on your TV you set the screen to stretch.
Every TV is different, but on my Sony HX929 this is under the menu item - Wide Mode. You get 3 options:
1. Normal - displays the resolution as-is, centered with no scaling
2. Full 1 - scales the image proportionally
3.
Full 2 - stretches the image to 16:9 <- This is what you need to do
By selecting Full 2, the TV is taking the signal from the Xbox - 512 pixel width image, which has been compressed by 10x11 pixel mode - and stretches it to 16:9 mode. This basically mimics the proper 640x448 SNES resolution. The 10x11 pixel mode is needed to compensate for the stretching involved. To my eyes, it seems perfect. Again, this won't help out SDTV users unfortunately.
Xbox - 480p - Stretched 16:9, 10x11 pixel mode

Xbox - 480p - Stretched 16:9, 10x11 pixel mode - with Scanlines (SLG3000)

Again, I think the blurriness shown here is likely due to the DVDO I'm using, but its hardly bad - especially with scanlines. This is a pretty accurate picture and probably better than you would get if you line-doubled a real SNES outputing RGB to an HDTV - or directly to an SDTV for that matter. Also, this is nearly indistinguishable from BNES outputing 1080p with video smoothing activated.
More in a bit.

Actually, looks like this is it. I just tried outputing to my TV via the Frosty VGA cable and it doesn't seem to want to sync the signal, even when passed through an Extron 203rxi (fancy VGA switch) which usually helps with this sort of thing. Sony HDTVs are picky these days. Anyway, that is all. I do think that the output via the Xbox could look 'sharper' if it were hooked up to a better device to transcode the component signal to VGA - but whatever, as I said, its a pretty accurate picture.
Edited by PhilExile, 18 September 2011 - 06:42 PM.