Moth3r: PAL, in theory, is in many ways superior to NTSC. In fact, the only downside to it (IMO) is that films are sped up 4% from 24FPS to 25FPS which causes a pitch change (which I personally find annoying, but only when songs are being played). PAL has more resolution than NTSC and there is no 3:2 pulldown when telecine-ing film. HOWEVER, because laserdiscs are an analogue format, you need a lot of good hardware in order to get a nice, clean signal. This is what makes the X0 so unique. If you want more information about the X0 player, go to the official X0 website.
In any case, there is no known PAL laserdisc player with such incredible hardware and because of that, there is a lot more noise/artifacts/etc.
The first post in this thread was by Laserman and in it, he posted some pictures to show how clean the X0 NTSC signal was compared to the PAL (captured from a 925, which, according to him, is the best PAL player around). Just from those posts, you see that the NTSC, despite its flaws, has a much better picture. In this case, practicality outweighs theory.
Go see for yourself: http://www.mudgee.net/ot/
iRatanplan: modifying an X0 has been talked about already in this thread, and its subject almost caused the the project to be abandoned. The simple answer is No. The hardware is dedicated NTSC (from what I read on the website, it has 5 different NTSC encoders), and plus motors are different between pal and ntsc laserdisc players (they spin at different speeds). Let's not also forget that the X0 is a 7,000 dollar player. Who the hell would want to modify a 7000 dollar investment?