I believe changing to ntsc in early boot menu will only change the refresh rate, so the colours will still be in pal mode and hence why it will be black and white on ntsc tvs that does not support pal.
Exactly.
I find it odd that modern ntsc tvs does not also support pal, as nearly all newer models of pal tvs also supports ntsc just nicely.. Why not also the other way around?
That's a good question, but probably because there isn't much demand for PAL compatibility (also it is more difficult to implement).
What I also dislike is the lack of RGB signal input on an NTSC tv, therefore it's not really an option to be used with an Amiga.
Because we use lots of PAL (but also NTSC) consoles (PS2, xbox...) where I work we have to use PAL/multisystem TVs. You can notice an amazing difference in picture quality when you hook up a PAL console -- even though it is essentialy the same TV, you can run the same software on it, even put it to PAL-60 Hz mode if you like, but the picture is never as blurred and as faded as with an NTSC console... The system just sucks. :-)