The people at the top will already have enough credits to do anything that they would please to be done. Also I think you should realize that reaching the top of that list is quite hard. As I am a sucker for statistics you could take a look at Top 10 Lowest Pings. There is also a per-country list too for countries with more than 10 endpoints. These should give a nice indication of how good your connectivity can be in certain countries.

And there is another new statistic called "Tunnel Uptime Statistics" which shows how long one is able to keep their tunnel up, which also proves the stability of the SixXS system.