Almost impossible to feel vibes from a halfshaft unless it's under power/acceleration. Remember, they spin 3.5 times slower than the driveshaft and are small in diameter. It's difficult to be out-of-balance by a great amount when the diameter is so small. CV shaft vibes will come from bad inner joints. I have never seen or read of an outer joint causing a vibration - noise yes, vibe no.
John - Lots of good info here:
http://hunter.com/pub/undercar/index.htm
and here:
http://www.gsp9700.com/pub/technical/index.cfm
Particularly interesting is how much road force is generated at various speeds by slightly out-of-balance tires.
Harvey - Ever ride a Vespa at high speed? Gyroscopic forces on a ten inch tire at 80 mph is one thing - try coupling that with a dynamic imbalance of the front wheel on a six lane highway during rush hour...
(in this case that smilie needs to be a LOT bigger)