Thanks for the kind words about my roll-over hoops! The onion shaped hoop works best for me although different shaped bots might benefit from different shaped hoops - its important to experiment. Another important feature is to always make the base of the hoops stick out further than the frame.

Advantages:
* Low-tech, no moving parts to break
* Cheap
* Works automatically
* Relatively low weight
* Provides shock absorption

Disadvantages:
* Can hang up on arena hazards
* Won't always work in arena corners
* Can get tangled with hammer and lifter bots

Looking at the servos mentioned above, the Seiko has almost 30X the torque of the Hobbyking one - I really doubt the 2 ft/pounds from the HK servo will turn your bot over. The are some mid-range options to look at: Invenscience has servos similar to the Seiko here http://www.invenscience.com/index_fi...tary_servo.htm . The i01853 has 8.3 ft/pounds of torque and as it has continuous rotation, you can gear it to produce whatever torque you need.

If you search thru the Aussie forum, Glen fitted Demon with a very effective self-righter made from a drill motor. The latest version with a custom metal case and clutch looks indestructible.