this is a pro apple forum and i am about to wade into shark infested waters, but here goes.
i have only two experiances with apple and ipods. both are with 30gb video's.
one could not be better and i love it to death, and did the same update you mentioned.
the other 30gb crashed immediatly upon doing the update. soooo bad, it needed to be replaced? sure, it was most likely a defective unit{good name for a boat by the way} and had more wrong with it that just an update issue, but it was only 2 months old fercrapsakes!
i bet 80% of users have no problem with the updates, but don't ever let anyone tell you there is no chance of a problem.
i'm not saying don't do it, just relateing my own experiance.
now,, don't everyone dump on me at once!