Groovy Mame + CRT Emu noob questions

[tadek]

Hi there.

After long trial and error process of configuring CRT Emu 2.0 beta and VMMaker modelines. I've managed to set up everything correctly.
Using Ati HD 4730 on iiyama vision master ( PC crt monitor) I have 240p, 248p, 256p, 264p, 272p, 280p, 296p, 304p, 320p at 120Hz. 400p and up modelines are at 60Hz.
I'm happy with the results but still have some questions

1. Is there any particular reason why 2560 resolution was chosen? Can i for example change it to 2880 or something else? Or will I get scaling artifacts...
2. Which renderer should i use? Currently it is set to d3d9ex but in newest alpha there's dropped support for it. My card does not support dx 11 so i presume bgfx will not work. So ddraw then? Asking just for future reference since using switchres v 0.015m for now.
3. What is the main advantage of black frame insertion on my set up? I have it on which halves the brightness. Which is not a bid deal on this monitor but still.
4. Dither. Is it possible to use anti-dither shader in groovy mame? Is such a shader exist for mame at all? Being looking for it and found nothing. On retroarch i'm using cbod which most of the times get the job done pretty nicely. And was wandering if such a thing exist in mame.

Thanks 

[haynor666]

2560 is 10x 256 so with games using 256 horizontal lines (majority in mame I think) probably You won't see any scalling artefacts. Personally I didn't have problems with 2560x240 and games using 256 or 320 horizontal lines but but I've seen problems with with games using 640 or higher horizontal lines.