The average of 100CC bikes is a question, it approaches over 50Km/L, but 70CC will go beyond this. So the people who love the ride would go for 125CC and people searching economy will opt 70CC.
Mechanics are real problem, they are incompetent with new bikes and their tools are no more useful with CD 100 or Junon. Therefore, they simply regret without going to performance and technology.
However, there are plenty of good mechanics of these bikes on their authorized service centers.