It is definitely possible. I can't quite remember where I read it (it may have been on their website), but I believe Slipstream (Team 254's 2011 robot) had a max speed of 20fps in one of their gears. I believe CD-Media has a few pictures of their gearbox around it. You may be interested in looking around for those and see if you can't get a good look at their gearing. When watching 254, I rarely saw them use it aside from the moments when they had to make quick runs across the field, and with 5 other robots on the field, that was not often. But it it would still be a nice feature to have in case of emergencies.
It is definitely possible.
Hope this helps!
-Leeland
Edit: Okay, 19.8.
This robot also weighs only 100lbs, but it should still be possible.