If you use an RGB monitor that doesn't scroll when it receives a PAL signal, you'll be fine for when you want to access the early startup menu and games. But yeah, there's a lot more available in PAL for this system, so not a bad idea to go 50hz native. It's what I did when I had my A1200. The few extra lines of resolution came in handy on the Workbench too

But as Tone suggested - you can force NTSC units to be PAL if you want. And yes, just because you have an RGB monitor, does not guarantee it'll handle PAL just fine. There are a couple of issues you might run into, such as the bottom of the screen slightly missing. May not scroll on you, but you also might not be able to view the entire screen unless you play around with the adjustments (which may or may not fully help either). Which monitor is it btw?