You did not mention:
- low noise
- crash resistance

List of disadvantages is also long.

 

From 25 years as a mechanic and industrial engineer, I can see the advantages and disadvantages of belt drive. Vibration dampening being the main advantage/ belt failure midflight (due to improper maintenance) could be problematic.

 

As @utrinque and @Beaver mentioned is true. However having owned the torque tube in some models and belt drive in other models I have observed the following..

Torque tube can be long lasting - but a real problem to change if you have an incident. And on many models it only takes clipping the tail to chip a gear. And @Crash Heligod normally makes sure its the gear inside the frame that is broken. Also vibration issues due to bent torque tube can be problematic when you start to turn up the headspeed.

Belts can be a real problem when they start to wear and fall off. I had this issue with the MINIP when using an overpowered motor. I destroyed 2 frames and broke 4 blades ,bent shafts etc due to the belt just falling off. Really hard to auto a 450 when you are doing pirofilips and then you realise the belt is no more. If you have any height you will usually do damage. I broke stuff 50% of the time.


Now something which can offset both of the negative points above. The goblins use a two stage belt. One thick and one thin. Today I met a 380 owner @josh who has put through 300 hard 3d flights on his 380. So this belt design looks so far on this model seems to be good. I cant vouch for the larger helis however. The minip has a 3mm belt. Too thing for high powered motors - i would only get 30ish hard smak flights.

Same can be said about torque tube. If the gears are stronger you will not have the chipping issue and the chipping issue normally applies to smaller (600 and below for trex) helis

The downside of the belts re smaller helis is less ability to auto.

So in summary IMO its very model dependent. Some models work better with belts due to design and the same with torque tube.