@jahc
NTSC Amigas are clocked at 7.14/14.28, while PAL-Amigas
are only 7.09/14.18. The NTSC-mode will still be quite near
to real NTSC and if you would use an NTSC-genlock (which
generates the clock for the Amiga), you would get 100% NTSC.
@Darth_X
Back in those days before I had an GFX-card I had all my Amigas
set to NTSC (the A2000 even hard-soldered), cos I couldn't stand
50Hz. Was also quite nice with the A2024 momitor because 1024x800
looked much better than 1024x1024, had less flicker (60Hz) and
even saved valuable chipmem.