In truth Thunder Tigre has at least admitted that there were some problems with their motors and have continuously refined and improved them from their introduction quite a few years ago. The biggest complaints with the TT36 heli was the carb which did have problems, It seems that the seals on the low speed needles were prone to disintegrating real fast and it gave you fits looking for an air leak.
However the newer series has been greatly improved the carb works perfectly and the motor certainly has more power then the os 32 SX and cost less to boot.
As to OS they have had their share of bad motors in the 50 years that they have been selling here,but they have never admitted that they made a bad one. Witness the ongoing problems with peeling liners in their FX series. Inevitabily if you need to send it in they will say that it was your fault not theirs.
In all honesty most motors today are worlds better then what was available even 20 years ago. CNC machinery just makes the fit and finish of todays offerings superb. Now the catch is the people using that equipment have to know what they are doing, give the Chinese another few years and they will get their act really together. Of course then the prices will go up dramatically too.