Long time, sporadic 'String or Binary data would be truncated.' Wisdom would be appreciated
I had similar error using different databases. All these errors were related to storing unicode varchar into non unicode varchar field. The problem was not displaying always, but it happened only when the text used contained multi byte characters.

So, first of all: does you database uses multi byte NVARCHAR instead of old style VARCHAR? And, second, are you really really really sure that your client cannot input text transmitted to your database server as multi byte characters?