I had a Harken 2655 break on me last night. It is the upper block in the Aussie halyard setup.
The Harken 2655 (40 mm Carbo fiddle) is an marginal choice for the Aussie halyard system on a 16. It only has a 485 lb working load and a 1620 lb breaking strength.
A better choice is the Harken 100 (double bullet block for wire). It has a working load of 750 lbs. Pair it with the Harken 099 (single bullet w/becket for wire). Both of those have a 2000 lb breaking strength.
Besides having a replacement on the way... I am pretty sure I just ordered what you are suggesting. Jim Sohn is setting me up.
so given that my experience seems to reinforce what you are saying.. maybe this needs updated...http://www.harken.com/OneDesign/hobie16.php
Sorry about the thread highjacking.. just wanted to put in my 2cents about Harken's service...