I've heard the 'only 6' story before, but I've been keeping track of VIN numbers and I believe there are more than 6 around. I would venture to guess that there probably were the original promotional 6 that circulated and additional custom paint work was done at the factory to produce more than 6.
What's the last 4 digits of your friends VIN? I'd like to add it to this thread:
Rennlist thread
Regardless, Pearl White is a gorgeous color and you have to see it in person to appreciate it. But Pearl Metallic colors have a reputation for being difficult to work with even for paint shops -- I've met a 911 owner who kept a jar of pearl (cheap ones) in case he ever needed to repaint a part.
As for the 911 vs 951 debate -- I go through it in my head occasionally -- but consider this: $20k will get you in a good mid 80's stock 911 (which is highly elegant and refined) whereas $20k will get you in an excellent highly modded 951 (powerful and raw). Pick your poison.