Bummer to hear about these breaking issues. This was a well-known issue with the 2005-2009 Sutras though. Like others have said, the 2010 design is much better. I've had by 2010 model for almost a year of hauling 30 to 50lb loads on the rear rack and haven't had a single problem.
100lbs of gear is pretty insane, regardless of what bike you have. If you don't break your braze-ons or dropouts, you'll break your rack, spokes, or wheels soon enough...
indyfabz - can't believe you toured carrying a medium format SLR and three lenses. a regular 35mm slr wasn't enough? lol... i think i could easily get by with a 35mm/full frame sensor and a few primes. probably wouldn't need more than a 24mm and a 105mm macro.