I'm with Harker...
I wouldn't stress about it, but I'd still do it. It is well worth the peace of mind - what is that saying about an ounce of prevention...?
I don't recall what the kit costs, but it can't be that much. Well under $50 if I recall correctly.
I've only done a handful (4-5), but they're generally a pretty easy job if you like to work on things. The only tricky part seems to be the linkage can be fiddly - not hard, just fiddly. My tohatsu has a roll pin setup that is a pain to work with - others I've had in the past had a more user friendly threaded rod linkage setup which I liked better.
Then again, an outboard mechanic I trust says to not replace them till the fail. Easy to say when you have a yard full of backup motors though... I only have one motor, so I tend to try to take extra good care of it. I got a good deal that I dont think I'll find again any time soon, so if this one goes it is so-long outboard...
Charlie