Thanks Calamity, but I have to admit that I don't really understand why the 24khz will be better? If it's rendered by emulators to 31khz, then the image quality should be even better than with 24khz, no?

Clearly 15khz games and pixel art are apart, but for 3D games?
I have to find a great 31Khz PC CRT monitor to try rendering high resolutions for emulated 3D games on a CRT, I guess it should be even better than playing with the original resolution, no? (If you think about the HD "remake" of Zelda WindWaker for the WiiU for example.)
P.S.: You're not the first one to say that he prefers a good 15khz fixed display over a tri-sync but is it true even when you consider the best tri-sync screens like a Sega New Net City (with the Toshiba PF), a Sega Blast City (with the Nanao MS2930/31) or a 29" NEC MultiSync CRT?