The speed isn\'t exactly an Hz/fps problem in this case. 50 Hz is enough to get a fast/ smooth image, but only if the developers used some time to adjust the speed for the Pal version( or just include a 60 Hz option to make it exactly to the NTSC).
So the real problem is that the developers made a fast NTSC-PAL conversion( consequence of a lack of time), so now we have a slower version of the games. But that is not the worst thing.
The worst thing is that in some cases( like SSX) they don\'t adjusted the frame transition also, so it calculates the objects coordinates like if it were running at 60 fps. It runs smooth during the first 50 fps, and then it recalculates the screen jumping from the frame 50 to the 60. So what we get?: smooth..... jump, smooth... jump.
Anyway, isn\'t that bad; i saw the same problem in some Pal DC 1st generation titles like VF3TB, and now most of the games runs smoothly or have a 60 Hz option.