NTSC and PAL just decide how the colour information is coded on the composite signal. You might be down by 100 lines but I have a feeling it won't matter. The chances are your plasma will have been built in the far east, therefore it probably has a multistandard chassis.

RGB and component don't need any complicated encoding on the chroma. They are simply colour difference signals. When I was over at NAB we had to hire a video projector, once we fed it with RGB it worked quite happily with the UK DVD player and the PAL disc we were using.

Just out of interest, how much of a saving are you making on this TV?