[sanddrag]

Some of the below may apply to transmissions of any type

Fast shifting on the fly.
The correct amount of backlash.
Along with the above, very very little room to be between gears, never a possiblity of both gears engaged at once.
Proper alignment.
No loads in undersirable directions (ie side loads)
Gears and shafts poperly spaced and captured - This one is very important. If you don't know how to do it or what I mean by that, we'll disuss it.
Both sides shifting at the same time.
All timed motors always spinning in the advanced direction while the robot is moving forward.
High durability.
Low maintainance.

Most of all, the driver nor software should not have to take any precausions when driving or shifting whatsoever. The transmission should perform sucessfully by its own mechanical doing no matter what the driver's input is. The mechanics of the transmission need to be robust enough to downshift at full speed and shift while switching between forward and reverse and shift up and down multiple times in a row very quickly and shift while turning clibming, etc any crazy thing you can think of (ie. drive into a wall)

The forces and situations that robots encounter in finals rounds I'm sure are far beyond any testing most teams do. Good drivers know the limits of their machines, but great drivers have machines with no limits. I say as soon as your robot runs (during the build period) you should run it hard. Put it through every torture imaginable. Then by the time ship comes, you'll hpefully have it made bulletproof.