[Mr. Ben]

I have the 16-50 and have not had any problems with the lens over the time that I've owned it (~8 months). I don't baby my lenses, but they usually aren't in very rough and tumble environments, though I can vouch for the water resistance.

Its a great lens, SDM failure be damned.

You can also check the Serial Number thread for more info, in general it seems like a problem that may have affected batches made earlier in production. If you can get a new piece, you should be OK.