3 years ago I wrote my first fully unit tested stored procedures that synchronizes (in very twisted way) few tables between two servers. One is in Europe second one in Asia and of course whole synchronization should be done in transaction (distributed of course).

It was my experiment, which took me 3 months to write it, and everyone was blaming me for doing it so long.

But when I installed it on the servers there was only ONE not so critical bug that showed up after 1,5 year or so.

Other than that this stored procedure is working without any problem for 3 years.

That convinced me completely.