Century servos are comparable to Hetic or any other micro servos out in the market, by far, it is better than. I have flown a lot of parkflyers. I can vouched and conclude, by far, that it is a great micro servo.
I wouldn't use them. Not unless I knew for a fact that they were a rebranded quality item from another maker like Futaba.
Futuba in the other hand is a peice of crap, sorry to say that, but it is, overly marked up, price wise and hetic just can hack the performance. Century only use their servo in the Humming bird and promotes being the only micro heli. servo. It's a Gem of a servo inside the little black box, labeled Century.
To prove my point.
S3107 Micro MG
Stall Torque 4.8V: 1.2kg.cm
Century Micro B.B. Servo (Universal)
Speed Torque Weight
4.8 volts 0.13 sec/60 1.3kg/cm 9g
6.0 volts 0.11 sec/60 1.5kq/cm 9g
Tested in 6.0volts
Torque (4.8V): 1.1kg.cm
Torque (6.0V): 1.3kg.cm
Note: I gathered these numbers from Futuba, Century, and Hetic website.