I don't think so. I would say it is a question of design and evolution. Lets not forget that Sirio is a young brand compared to others, and they've been improving their engines over time.
With the new Evo 2 engines, carb problems are a question of the past and I must say it is the best and most reliable carb i've had so far. I even use it on my Nova based engines. The crank hardness seems to have been corrected now, so I would say they do care and improve their engines constantly.
To finish, I would say that they have the right price/performance equilibrium.
I will keep using these engines because when broken in correctly and tuned correctly, they give awesome performance.

AFM