If it helps, I have an Amiga 500+ PAL system and have recently made some interesting revelations.
It really depends on what you want to do whether you need a PAL or NTSC system. If you want to play demos and games from over the pond, you'll probably want to stick with the PAL system. USA games are probably the only reason to use an NTSC system.
If you plan to use a modern version of AmigaOS, a PAL system will work just fine thanks to the NTSC monitor driver. I *thought* I had an NTSC system until recently when I finally looked up the 2MB Agnus and found it really is PAL. Connecting it to my Dell LCD monitor confirmed this: the early startup menu was 50Hz.
That explains why game and music timing were different, and also why startup graphics which came up before Workbench didn't center vertically on the screen as expected. None of this bothered me in the five years I used this particular system, and I'm sure it won't bother you.
