I once saw a Cd70 rider giving a very tough time to a Cg125 on Wahdat road. It was 5pm and the street was very congested. The simple reason for cd70 having the lead was because he was willing to take more 'risk' than the Cg rider, i.e. he was passing more closer to the cars and making more abrupt sharp turns. The thing with Gs150 and RP is that you cannot be extremely 'suicidal' on this bike. As they are a bit wider and longer than Cg and so your bike will not 'fit' in-between two cars on a normal traffic road and also you will not be able to go make 'supposedly motoGP styled turns'.
On a road where traffic is less and it is safe to ride at higher speeds, Cg will take initial lead due to its higher pick but soon Gs150 and RP will overtake it and after that the Cg rider can do whatever he wants, like pull the clutch or put his head down, he will NOT be able to overtake either Gs or Rp.
So in short, if you like to put your life at risk and declare a do-or-die category war on every bike and car within city traffic, then cg125 should be your obvious choice as it is one of the best lane-splitter due to its narrow body.
On the other hand, if you actually want to know which bikes have highest top speed in local market, then the answer is Gs and Rp.
