Hi Travis,
I think you will find the following threads helpful:
http://www.chiefdelphi.com/forums/sh...ight=worm+gear
http://www.chiefdelphi.com/forums/sh...ight=worm+gear
http://www.chiefdelphi.com/forums/sh...ad.php?t=41482
The general consensus among teams that have tried using worm gears in their drivetrains is that mechanical alignment is of the utmost importance to maximize your (already reduced) efficiency and avoid breaking things. Also, make sure you think long and hard about what materials to use for your worm. Also, be cognizant of the effects of sudden slopping and collisions with robots and field elements on the teeth of your worm.
As far as running your worm at 5000+ RPM, while YMMV, I would doubt that an un-reduced CIM would have the torque to overcome the considerable friction in a worm drive.
Personally, I would reconsider any design using worms in the drive train - there are other (easier) ways to be non-backdriveable besides worm gears.
Hope this helps.